Device and method of detecting flow rate/liquid kind, and device and method of detecting liquid kind

ABSTRACT

A flow rate/liquid type detecting method for detecting the flow rate of a fluid and, at the same time, detecting any one of or both the type of the fluid and the concentration of the fluid, characterized in that: by using a flow rate/liquid type detecting apparatus comprising a main passage through which a fluid to be detected flows, an auxiliary passage branched from the main passage, and a flow rate/liquid type detecting sensor device provided in the auxiliary passage, is provided, and in conducting any one of or both the detection of the type of the fluid to be detected and the detection of the concentration of the fluid to be detected, an auxiliary passage opening/closing valve is closed, and the fluid to be detected is allowed to temporarily stay within the flow rate/liquid type detecting sensor device to conduct any one of or both the detection of the liquid type and the detection of the concentration, and in detecting the flow rate of the fluid to be detected, the auxiliary passage opening/closing valve is opened to allow the fluid to be detected to flow into the flow rate/liquid type detecting sensor device to detect the flow rate.

TECHNICAL FIELD

The present invention relates to a flow rate/liquid type detectingapparatus and a flow rate/liquid type detecting method for detecting thetype, concentration and flow rate of fluids, for example, gasoline or alight oil as a fuel in automobiles, and organic solutions in plants andthe like, and a liquid type detecting apparatus and a liquid typedetecting method.

BACKGROUND ART

Automotive exhaust gases contain contaminants such as unburnedhydrocarbons (HCs), NOx gases, and SOx gases. An attempt to reduce thesecontaminants has hitherto been made, for example, by a method in which,for SOx, S in gasoline is removed, or unburned HCs are burned in thepresence of a catalyst.

Specifically, as shown in FIG. 17, in an automotive system 100, air isintroduced through an automatic element (filter) 102, is then passedthrough an air flow rate sensor 104, and is fed into an engine 106. Onthe other hand, a gasoline within a fuel tank 108 is fed through a fuelpump 110 into the engine 106.

Further, the automotive system 100 is constructed so that, based on theresults of detection with an A/F sensor 112, fuel injection in theengine 106 is controlled by a fuel injection control device 114 so thatthe air-fuel ratio is brought to a predetermined theoretical air-fuelratio.

An exhaust gas from the engine 106 is fed into a catalyst device 116where hydrocarbons (HCs) contained in the exhaust gas are burned. Theexhaust gas is then passed through an oxygen concentration sensor 118and is discharged as an exhaust gas.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In the above automotive system, as shown in FIG. 18, various gasolinesdifferent from each other in distillation properties (different fromeach other in easiness in evaporation) are sold around the world.

Specifically, FIG. 18 shows distillation properties of gasolines, thatis, the relationship between % distillate and temperature. For example,50% (T50) on the abscissa indicates the temperature (° C.) at which 50%of various gasolines are evaporated.

As shown in FIG. 18, for example, as compared with standard gasoline No.3, gasoline A2 is the heaviest (difficult to evaporate) gasoline, andgasoline No. 7 is the lightest (easy to evaporate) gasoline.

Accordingly, as shown in Table 1 below, for example, in an automobileregulated so that, for standard gasoline No. 3, the air-fuel ratio is atheoretical one, when standard gasoline No. 3 is replaced with theheavier gasoline A2, in particular, the torque is insufficient when anengine is started, particularly when an engine in which a catalystdevice is not in a warmed state is started, although the content of HCsin the exhaust gas is low.

On the contrary, when gasoline No. 7 which is a lighter gasoline isused, the air-fuel ratio exceeds the theoretical air-fuel ratio althoughthe torque is satisfactory. In this case, in particular, when an engineis started, particularly when an engine in which a catalyst device isnot in a warmed state is started, the content of HCs in the exhaust gasis so large that the influence on the environment is disadvantageouslylarge.

TABLE 1 Regulation Exhaust gasoline Gasoline used Torque gas (HC) No. 3No. 3 ◯ ◯ No. 3 A2 X ◯ No. 3 No. 7 ◯ X

In patent document 1 (Japanese Laid-Open Patent Publication No. Hei 11(1999)-153561), the present inventors have already proposed a fluiddetecting method which comprises energizing a heating element togenerate heat, heating a temperature detector with this heat, giving athermal influence on thermal transfer from the heating element to thetemperature detector by the fluid to be detected, and judging the typeof the fluid to be detected based on electrical output corresponding tothe electrical resistance of the temperature detector. In this method,energization of the heating element is periodically carried out.

In this fluid detection method, however, since the heating elementshould be periodically energized (using multipulses), a lot of time isrequired for the detection and, consequently, it is difficult toinstantaneously detect the fluid. Further, in this method, for example,fluid detection can be carried out using representative values forsubstances considerably different from each other in properties, forexample, for water, air, and oil. However, for the detection between theabove gasolines which have considerably mutually close properties,accurate and rapid detection are difficult.

On the other hand, in consideration of the influence of NOx in anexhaust gas on environment, for example, in order to reduce Nox in theexhaust gas from an automotive fuel such as gasoline or light oils, amethod has recently been proposed in which a urea solution is fed into acatalyst device 116 to reduce NOx into N₂ gas which is an unharmful gas.

Specifically, as shown in FIG. 19, an automotive system 100 isconstructed so that a urea solution is supplied, through a urea solutionfeed mechanism 130 comprising a urea solution tank 132 storing a ureasolution, a urea pump 134, and a urea spray device 136 for spraying aurea solution supplied from the urea pump 134 toward the upstream sideof a catalyst device 116, to the upstream side of the catalyst device116.

In this automotive system, in order to efficiently cause a reductionreaction on the upstream side of the catalyst device 116 without causingsolidification of the urea solution, for example, the urea solutionpreferably comprises 32.5% of urea and 67.5% of H₂O.

For this reason, in the prior art technique, an NOx sensor 140 and anNOx sensor 142 are provided respectively on the upstream side anddownstream side of the catalyst device 116 to measure the concentrationof NOx and thus to judge whether or not the concentration of ureasprayed toward the upstream side of the catalyst device 116 is constant.

However, since, the NOx sensors 140, 142 measure the urea concentrationbased on the results of a reduction in NOx, it is impossible topreviously detect the concentration of urea within the urea solutiontank 132 or urea to be sprayed. Further, the sensitivity of the NOxsensors 140, 142 was not so good.

Further, in all the above automotive systems using gasoline and a ureasolution, grasping the flow rate and liquid type of gasoline and theflow rate and concentration of the urea solution is important forcontrolling an engine and a catalyst device to reduce HCs and NOx.

Regarding an apparatus for detecting the flow rate of this fluid, patentdocument 2 (Japanese Laid-Open Patent Publication No. Hei 11(1999)-118566) proposes a thermal type flow sensor that uses anindirectly heated flow sensor using a thin-film element and an electriccircuit including a bridge circuit for obtaining electrical outputcorresponding to the flow rate of the fluid, and detects the flow rateof the fluid to be detected by taking advantage of voltage applied to aheating element.

However, in the flow sensor disclosed in patent document 2 (JapaneseLaid-Open Patent Publication No. Hei 11 (1999)-118566), although theflow rate of the fluid can be detected, the detection of the liquid typeand concentration of the fluid simultaneously with the detection of theflow rate of the fluid is impossible.

Accordingly, in order to grasp the flow rate and type of gasoline andthe flow rate and concentration of a urea solution, in addition to theabove detecting apparatus for detecting the type of gasoline andapparatus for measuring the concentration of the urea solution, a flowrate measuring apparatus as disclosed in patent document 2 (JapaneseLaid-Open Patent Publication No. Hei 11 (1999)-118566) should beseparately provided, often leading to an increase in size of the system.

As with the automotive system using the above fluid, systems usingkerosene and plants using a solution of a substance dissolved in anorganic solvent requires the detection of flow rate and concentration,posing the same problem.

Patent document 1: Japanese Laid-Open Patent Publication No. Hei 11(1999)-153561 (particularly, see paragraphs [0042] to [0049])

Patent document 2: Japanese Laid-Open Patent Publication No. Hei 11(1999)-118566

Under these circumstances, an object of the present invention is toprovide a flow rate/liquid type detecting apparatus and a flowrate/liquid type detecting method that can detect the flow rate of afluid and, at the same time, can detect the liquid type andconcentration of the fluid in a compact, accurate and rapid manner.

Another object of the present invention is to provide a flow rate/liquidtype detecting apparatus for an automobile and a flow rate/liquid typedetecting method for an automobile, using the above flow rate/liquidtype detecting apparatus and flow rate/liquid type detecting method.

A further object of the present invention is to provide an automotiveexhaust gas reducing apparatus and an automotive exhaust gas reducingmethod, using the above flow rate/liquid type detecting apparatus andflow rate/liquid type detecting method, that can efficiently reduce theexhaust gas and can improve fuel consumption.

Further, under the above circumstances, another object of the presentinvention is to provide a liquid type detecting apparatus and a liquidtype detecting method that can detect the liquid type and concentrationof the fluid in a compact, accurate and rapid manner.

Still another object of the present invention is to provide a liquidtype detecting apparatus for an automobile and a liquid type detectingmethod for an automobile, using the above liquid type detectingapparatus and liquid type detecting method.

A further object of the present invention is to provide an automotiveexhaust gas reducing apparatus and an automotive exhaust gas reducingmethod, using the above liquid type detecting apparatus and liquid typedetecting method, that can efficiently reduce the exhaust gas and canimprove fuel consumption.

SUMMARY OF THE INVENTION

The present invention has been made with a view to solving the aboveproblems of the prior art and to attaining the objects of the presentinvention, and according to the present invention, there is provided aflow rate/liquid type detecting apparatus for detecting the flow rate ofa fluid and, at the same time, detecting any one of or both the type ofthe fluid and the concentration of the fluid, comprising:

a main passage through which a fluid to be detected flows;

an auxiliary passage branched from said main passage;

a flow rate/liquid type detecting sensor device provided in saidauxiliary passage;

an auxiliary passage opening/closing valve provided in said auxiliarypassage, for controlling the flow of the fluid to be detected into saidflow rate/liquid type detecting sensor device; and

a control unit for controlling said flow rate/liquid type detectingsensor and said auxiliary passage opening/closing valve,

said control unit being constructed so as to conduct control in such amanner that;

in conducting any one of or both the detection of the type of said fluidto be detected and the detection of the concentration of said fluid tobe detected, said auxiliary passage opening/closing valve is closed, andsaid fluid to be detected is allowed to temporarily stay within saidflow rate/liquid type detecting sensor device to conduct any one of orboth the detection of the liquid type and the detection of theconcentration, and;

in detecting the flow rate of the fluid to be detected, said auxiliarypassage opening/closing valve is opened to allow the fluid to bedetected to flow into said flow rate/liquid type detecting sensor deviceto detect the flow rate.

Further, according to the present invention, there is provided a flowrate/liquid type detecting method for detecting the flow rate of a fluidand, at the same time, detecting any one of or both the type of thefluid and the concentration of the fluid, characterized in that:

by using a flow rate/liquid type detecting apparatus comprising;

a main passage through which a fluid to be detected flows,

an auxiliary passage branched from said main passage, and

a flow rate/liquid type detecting sensor device provided in saidauxiliary passage, is provided, and

in conducting any one of or both the detection of the type of said fluidto be detected and the detection of the concentration of said fluid tobe detected, said auxiliary passage opening/closing valve is closed, andsaid fluid to be detected is allowed to temporarily stay within saidflow rate/liquid type detecting sensor device to conduct any one of orboth the detection of the liquid type and the detection of theconcentration, and

in detecting the flow rate of the fluid to be detected, said auxiliarypassage opening/closing valve is opened to allow the fluid to bedetected to flow into said flow rate/liquid type detecting sensor deviceto detect the flow rate.

According to the above construction, in conducting any one of or boththe detection of the type of said fluid to be detected and the detectionof the concentration of said fluid to be detected, any one of or boththe detection of the liquid type and the detection of the concentrationcan be carried out in an accurate and rapid manner by closing theauxiliary passage opening/closing valve and allowing the fluid to bedetected to temporarily stay within said flow rate/liquid type detectingsensor device.

On the other hand, in detecting the flow rate of the fluid to bedetected, the flow rate can be detected by opening the auxiliary passageopening/closing valve and allowing the fluid to be detected to flow intothe flow rate/liquid type detecting sensor device.

Thus, the liquid type and concentration of a fluid can also be detectedsimultaneously with the detection of the flow rate of the fluid in anaccurate and rapid manner. Further, simultaneous detection of the flowrate of the fluid and the detection of the liquid type and concentrationof the fluid can be realized in a single flow rate/liquid type detectingapparatus. Therefore, detection in a compact manner can be realized,and, for example, when this is applied to an automotive system, thewhole system can be rendered compact.

The present invention is characterized in that a non-return valve isprovided on the downstream side of said flow rate/liquid type detectingsensor device in said auxiliary passage.

As described above, the non-return valve is provided on the downstreamside of the flow rate/liquid type detecting sensor device in theauxiliary passage. Therefore, if backward flow is caused, for example,due to the occurrence of pulsating flow depending upon the type of apump as a liquid feed device for the flow of a fluid, and the type of adrive system, this backward flow can be prevented.

Since the backward flow of the fluid within the flow rate/liquid typedetecting sensor device can be prevented, the detection of liquid type,the detection of concentration, and the detection of flow rate can becarried out in an accurate and rapid manner without undergoing theinfluence of backward flow of the fluid.

The present invention is characterized in that a main passageopening/closing valve for controlling the flow of said fluid to bedetected into said main passage is provided in said main passage.

The flow rate/liquid type detecting apparatus according to the presentinvention is characterized in that said control unit is constructed soas to conduct control in such a manner that:

when the flow rate of said fluid to be detected is small, said mainpassage opening/closing valve is closed, and

when the flow rate of said fluid to be detected is large, said mainpassage opening/closing valve is opened.

The flow rate/liquid type detecting method according to the presentinvention is characterized in that control is carried out so that,

when the flow rate of said fluid to be detected is small, said mainpassage opening/closing valve is closed, and

when the flow rate of said fluid to be detected is large, said mainpassage opening/closing valve is opened.

When the flow rate of the fluid to be detected is small, closing of themain passage opening/closing valve allows the fluid to be detected toflow into the auxiliary passage to ensure the flow rate of the fluidnecessary for the detection in the flow rate/liquid type detectingsensor device.

On the other hand, when the flow rate of the fluid to be detected islarge, opening of the main passage opening/closing valve allows thefluid to flow into the main passage to lower the flow rate of the fluidwhich flows into the auxiliary passage and thus to ensure the flow rateof the fluid necessary for the detection in the flow rate/liquid typedetecting sensor device.

Accordingly, the present invention can be utilized even when the dynamicrange of the flow rate is large, and, thus, it is possible to provide aflow rate/liquid type detecting apparatus and a flow rate/liquid typedetecting method with a wide sensitivity range.

Further, the present invention is characterized in that an orifice isprovided in the main passage.

Since an orifice is provided in the main passage, even when the pressureloss within the main passage is so small that the fluid is less likelyto flow into the auxiliary passage, the pressure loss in the mainpassage can be increased by the orifice. As a result, the fluid can beallowed to flow at a given flow rate necessary for detection into theauxiliary passage and, thus, the above detection can be reliably carriedout.

The flow rate/liquid type detecting apparatus according to the presentinvention is characterized in that:

said flow rate/liquid type detecting sensor device comprises;

a flow rate/liquid type detecting chamber for allowing the fluid to bedetected which has been introduced into a flow rate/liquid typedetecting sensor device body to temporarily stay therein,

a flow rate/liquid type detecting sensor heater provided within saidflow rate/liquid type detecting chamber, and

a liquid temperature sensor spaced by a given distance from said flowrate/liquid type detecting sensor heater and provided within said flowrate/liquid type detecting chamber,

said flow rate/liquid type detecting sensor heater comprising a heaterand a flow rate/liquid type detecting liquid temperature sensor providedin the vicinity of said heater, and

said flow rate/liquid type detecting apparatus is constructed so that;

in conducting any one of or both the detection of the type of said fluidto be detected and the detection of the concentration of said fluid tobe detected,

a pulse voltage is applied to said flow rate/liquid type detectingsensor heater for a predetermined period of time,

the fluid to be detected which temporarily stays within said flowrate/liquid type detecting chamber is heated with the heater, and

any one of or both the liquid type of the fluid and the concentration ofthe fluid are detected, by a voltage output difference V0, correspondingto a difference in temperature between the initial temperature and thepeak temperature of said flow rate/liquid type detecting liquidtemperature sensor,

in detecting the flow rate of said fluid to be detected,

a pulse voltage is applied to said flow rate/liquid type detectingsensor heater for a predetermined period of time,

the fluid to be detected which flows through said flow rate/liquid typedetecting chamber is heated with the heater, and

the flow rate is detected, by a voltage output difference V0,corresponding to a difference in temperature between the initialtemperature and the peak temperature of said flow rate/liquid typedetecting liquid temperature sensor.

The flow rate/liquid type detecting method according to the presentinvention is characterized in that

said flow rate/liquid type detecting sensor device comprises:

a flow rate/liquid type detecting chamber for allowing the fluid to bedetected which has been introduced into a flow rate/liquid typedetecting sensor device body to temporarily stay therein,

a flow rate/liquid type detecting sensor heater provided within saidflow rate/liquid type detecting chamber, and

a liquid temperature sensor spaced by a given distance from said flowrate/liquid type detecting sensor heater and provided within said flowrate/liquid type detecting chamber,

said flow rate/liquid type detecting sensor heater comprising a heaterand a flow rate/liquid type detecting liquid temperature sensor providedin the vicinity of said heater, and

said flow rate/liquid type detecting method comprising the steps of;

in conducting any one of or both the detection of the type of said fluidto be detected and the detection of the concentration of said fluid tobe detected,

applying a pulse voltage to said flow rate/liquid type detecting sensorheater for a predetermined period of time,

heating with the heater, the fluid to be detected which temporarilystays within said flow rate/liquid type detecting chamber,

detecting any one of or both the liquid type of the fluid and theconcentration of the fluid, by a voltage output difference V0,corresponding to a difference in temperature between the initialtemperature and the peak temperature of said flow rate/liquid typedetecting liquid temperature sensor,

in detecting the flow rate of said fluid to be detected,

applying a pulse voltage to said flow rate/liquid type detecting sensorheater for a predetermined period of time,

heating, with the heater, the fluid to be detected which flows throughsaid flow rate/liquid type detecting chamber, and

detecting the flow rate by a voltage output difference V0, correspondingto a difference in temperature between the initial temperature and thepeak temperature of said flow rate/liquid type detecting liquidtemperature sensor.

In the adoption of the above construction, what is required is only toapply pulse voltage for a predetermined period of time. Therefore, thetype and concentration and flow rate of a fluid such as gasoline can bedetected in an accurate and rapid manner by heating for a short periodof time, and further, without heating the fluid such as gasoline to atemperature at which the fluid ignites.

Specifically, the above construction utilizes a correlation between thekinematic viscosity of the fluid and the sensor output, utilizes naturalconvection, and one pulse applied voltage. Threfore, the type andconcentration and flow rate of the fluid can be detected in an accurateand rapid manner.

Further, the present invention is characterized in that the voltageoutput difference V0 is the difference in voltage between an averageinitial voltage V1, which is determined by sampling the initial voltagebefore the application of said pulse voltage by a predetermined numberof times, and an average peak voltage V2, which is determined bysampling the peak voltage after the application of said pulse voltage bya predetermined number of times, that is,V0=V2−V1.

When the above construction is utilized, the voltage output differenceV0 can be accurately determined based on the average value of apredetermined number of times of sampling for one pulse applied voltage.Therefore, the type, concentration and flow rate of a fluid can bedetected in an accurate and rapid manner.

The flow rate/liquid type detecting apparatus according to the presentinvention is characterized in that said control unit is constructed sothat:

based on calibration curve data as a correlation between temperature andvoltage output difference, for predetermined reference fluids previouslystored in said control unit,

anyone of or both the liquid type and concentration of said fluid to bedetected are detected using said voltage output difference V0 obtainedfor said fluid to be detected.

The flow rate/liquid type detecting method for gasoline according to thepresent invention is characterized in that:

based on calibration curve data as a correlation between temperature andvoltage output difference, for predetermined reference fluids previouslystored in said control unit,

any one of or both the liquid type and concentration of said fluid to bedetected are detected using said voltage output difference V0 obtainedfor said fluid to be detected.

According to the above construction, based on previously storedcalibration curve data as a correlation between temperature and voltageoutput difference, for predetermined reference fluids, the type andconcentration of the fluid are detected using the voltage outputdifference V0 obtained for the fluid to be detected. Therefore, the typeand concentration of a fluid can be detected in a more accurate andrapid manner.

The flow rate/liquid type detecting apparatus according to the presentinvention is characterized in that said control unit is constructed sothat:

a voltage output Vout for the voltage output difference V0 at ameasuring temperature for said fluid to be detected is corrected in acorrelation with the output voltage for the voltage output difference atthe measuring temperature for a predetermined threshold reference fluid.

The flow rate/liquid type detecting method according to the presentinvention is characterized in that:

a voltage output Vout for the voltage output difference V0 at ameasuring temperature for said fluid to be detected is corrected in acorrelation with the output voltage for the voltage output difference atthe measuring temperature for a predetermined threshold reference fluid.

By adopting such a construction, a voltage output Vout for the voltageoutput difference V0 at a measuring temperature for said fluid to bedetected is corrected in a correlation with the output voltage for thevoltage output difference at the measuring temperature for apredetermined threshold reference fluid. Therefore, the influence of thetemperature on the voltage output difference V0 can be eliminated toimpart a more accurate correlation between the voltage output Vout andthe properties of gasoline. As a result, the type, concentration andflow rate of the fluid can be detected in a more accurate and rapidmanner.

The flow rate/liquid type detecting apparatus according to the presentinvention is characterized in that said control unit is constructed sothat:

based on calibration curve data as a correlation between temperature andvoltage output difference, for predetermined reference fluids previouslystored in said control unit,

the flow rate of said fluid to be detected is detected using saidvoltage output difference V0 obtained for said fluid to be detected.

The flow rate/liquid type detecting method according to the presentinvention is characterized in that:

based on previously stored calibration curve data as a correlationbetween temperature and voltage output difference for predeterminedreference fluids,

the flow rate of said fluid to be detected is detected using saidvoltage output difference V0 obtained for said fluid to be detected.

According to the above construction, based on previously storedcalibration curve data as a correlation between temperature and voltageoutput difference for predetermined reference fluids, the flow rate ofthe fluid is detected using said voltage output difference V0 obtainedfor said fluid to be detected, Therefore, the flow rate of a fluid canbe detected in a more accurate and rapid manner.

Further, the present invention is characterized in that said flowrate/liquid type detecting sensor heater is a laminated flow rate/liquidtype detecting sensor heater in which a heater and a flow rate/liquidtype detecting liquid temperature sensor are laminated through aninsulating layer.

By adopting such a construction, since any mechanically moved mechanismpart does not exist, malfunction derived from a deterioration with theelapse of time or the presence of foreign matter in the fluid or thelike does not occur. Consequently, the liquid type, concentration, andflow rate of the fluid can be detected in an accurate and rapid manner.

Furthermore, since the sensor part can be constructed in a very smallsize, the thermal response is very good and the liquid type,concentration, and flow rate of the fluid can be accurately detected.

Further, the present invention is characterized in that the heater insaid flow rate/liquid type detecting sensor heater and said flowrate/liquid type detecting liquid temperature sensor each areconstructed so as to come into contact with the fluid to be detectedthrough a metallic fin.

According to the above construction, the heater of the flow rate/liquidtype detecting sensor heater and the flow rate/liquid type detectingliquid temperature sensor do not come into direct contact with a fluidto be detected. Therefore, malfunction derived from a deterioration withthe elapse of time or the presence of foreign matter or the like in thefluid does not occur. Consequently, the type, concentration, and flowrate of the fluid can be detected in an accurate and rapid manner.

Furthermore, the present invention is characterized in that said liquidtemperature sensor is constructed so as to come into contact with thefluid to be detected through said metallic fin.

By adopting such a construction, the liquid temperature sensor does notcome into direct contact with a fluid to be detected. Therefore,malfunction derived from a deterioration with the elapse of time or thepresence of foreign matter or the like in the fluid does not occur.Consequently, the type, concentration and flow rate of the fluid can bedetected in an accurate and rapid manner.

The flow rate/liquid type detecting apparatus for an automobileaccording to the present invention is adapted for the detection of theflow rate and type of gasoline or a light oil and is characterized inthat:

any of the above flow rate/liquid type detecting apparatuses is providedwithin a fuel tank or on the upstream side or downstream side of a fuelpump.

The flow rate/liquid type detecting method for an automobile accordingto the present invention is adapted for detecting the flow rate and typeof gasoline or a light oil, comprising:

detecting the flow rate and type of said gasoline or light oil within afuel tank or on the upstream side or downstream side of a fuel pump, byusing any of the above flow rate/liquid type detecting methods.

By adopting such a construction, in automobiles, the type of gasoline ora light oil can be detected in an accurate and rapid manner.

The automotive exhaust gas reduction apparatus according to the presentinvention is adapted for reducing an exhaust gas from an automobile,comprising:

any of the above flow rate/liquid type detecting apparatuses, which isprovided within a fuel tank or on the upstream side or downstream sideof a fuel pump; and

an ignition timing control unit for regulating ignition timing based onthe flow rate and type of the gasoline or light oil, which is detectedby said flow rate/liquid type detecting apparatus.

The automotive exhaust gas reduction method according to the presentinvention is adopted for reducing an exhaust gas from an automobile,comprising the steps of:

detecting the flow rate and type of the gasoline or light oil within afuel tank or on the upstream side or downstream side of a fuel pump, byusing any of the above flow rate/liquid type detecting methods, and

regulating an ignition timing based on the flow rate and type of thegasoline or light oil which is detected by said flow rate/liquid typedetecting apparatus.

By adopting such a construction, ignition timing can be adjusted basedon the results of detection of the flow rate and type of gasoline or alight oil. Therefore, proper ignition timing depending upon the flowrate and type of gasoline or a light oil can be provided.

Accordingly, in particular, even when an engine is started, particularlywhen an engine in which a catalyst device is not in a warmed state isstarted, the content of HCs and NOx in the exhaust gas can be reduced,and, at the same time, fuel consumption can be improved, without causinga reduction in torque.

The automotive exhaust gas reduction apparatus according to the presentinvention is adopted for reducing an exhaust gas from an automobile,comprising:

any of the above flow rate/liquid type detecting apparatuses, which isprovided within a fuel tank or on the upstream side or downstream sideof a fuel pump; and

a gasoline or light oil compression control unit for regulating thecompression ratio of the gasoline or light oil based on the flow rateand type of the gasoline or light oil, which is detected by said flowrate/liquid type detecting apparatus.

The automotive exhaust gas reduction method according to the presentinvention is adapted for reducing an exhaust gas from an automobile,comprising the steps of:

detecting the flow rate and type of the gasoline or light oil within afuel tank or on the upstream side or downstream side of a fuel pump, byusing any of the above flow rate/liquid type detecting methods, and

regulating the compression ratio of the gasoline based on the flow rateand type of the gasoline or light oil which is detected by said flowrate/liquid type detecting apparatus.

By adopting such a construction, the compression ratio of gasoline or alight oil can be adjusted based on the results of detection of the flowrate and type of gasoline or a light oil. Therefore, proper compressionratio of gasoline or a light oil depending upon the type of gasoline canbe provided.

Accordingly, in particular, even when an engine is started, particularlywhen an engine in which a catalyst device is not in a warmed state isstarted, the content of HCs and NOx in the exhaust gas can be reduced,and, at the same time, fuel consumption can be improved, without causinga reduction in torque.

The automotive exhaust gas reduction apparatus according to the presentinvention is adopted for reducing an exhaust gas from an automobile,comprising:

a urea solution feed mechanism for feeding a urea solution to theupstream side of a catalyst device,

said urea solution feed mechanism comprising a urea solution tank forstoring a urea solution, a urea pump, a urea spray device for sprayingthe urea solution, which is supplied from said urea pump, toward theupstream side of said catalyst device, and

any of the above flow rate/liquid type detecting apparatuses, which isprovided within said urea tank or on the upstream side or downstreamside of said urea pump.

The automotive exhaust gas reduction method according to the presentinvention is adapted for reducing an exhaust gas from an automobile,comprising the steps of:

supplying a urea solution to the upstream side of the catalyst device,through a urea solution feed mechanism comprising a urea solution tankfor storing a urea solution, a urea pump, and a urea spray device forspraying the urea solution, which is supplied from said urea pump,toward the upstream side of said catalyst device, and

detecting the flow rate and urea concentration of the urea solutionwithin said urea tank or on the upstream side or downstream side of saidurea pump, by using any of the above flow rate/liquid type detectingmethods.

According to the above construction, in order to efficiently cause areduction reaction on the upstream side of the catalyst device withoutcausing solidification of the urea solution, whether or not, forexample, the urea solution comprises 32.5% of urea and 67.5% of H₂O canbe judged in an accurate and rapid manner.

Therefore, the urea concentration of the urea solution in the urea tankcan be kept at a predetermined concentration, and, thus, the NOx in theexhaust gas can be decreased to a very low level by reduction.

Further, the present invention has been made with a view to solving theabove problems of the prior art and attaining the object of the presentinvention, and the liquid type detecting apparatus according to thepresent invention is adapted for detecting any one of or both the liquidtype and concentration of a fluid, comprising:

a liquid type detecting chamber for allowing a fluid to be detectedwhich has been introduced into a liquid type detecting apparatus body totemporarily stay therein,

a liquid type detecting sensor disposed within said liquid typedetecting chamber, and

a flow control plate provided within said liquid type detecting chamberso as to surround said liquid type detecting sensor.

Further, the liquid type detecting method according to the presentinvention is adapted for detecting any one of or both the liquid typeand concentration of a fluid, comprising the steps of:

providing a liquid type detecting apparatus comprising;

a liquid type detecting chamber for allowing a fluid to be detectedwhich has been introduced into a liquid type detecting apparatus body totemporarily stay therein,

a liquid type detecting sensor disposed within said liquid typedetecting chamber, and

a flow control plate provided within said liquid type detecting chamberso as to surround said liquid type detecting sensor, and

stopping the introduction of the fluid to be detected into said liquidtype detecting apparatus body,

allowing the fluid to be detected to temporarily stay within said liquidtype detecting chamber, and

conducting the detection of any one of or both the liquid type andconcentration of the fluid to be detected.

According to the above construction, in the case where the introductionof the fluid to be detected into the liquid type detecting apparatusbody is stopped to allow the fluid to be detected to temporarily staywithin the liquid type detecting chamber, the flow of the fluid to bedetected within the liquid type detecting chamber is suppressed by theflow control plate. As a result, the flow of the fluid to be detectedaround the liquid type detecting sensor, which is located within theflow control plate surrounded by this flow control plate, isinstantaneously stopped.

Therefore, in detecting the liquid type and concentration with theliquid type detecting sensor, the flow of the fluid to be detected doesnot occur, and, further, turbulence of the fluid to be detected by thevibration does not occur. Thus, the influence on the detection of theliquid type and concentration of the fluid to be detected can beprevented. Consequently, the liquid type and concentration of the fluidto be detected can be accurately measured.

Further, since a liquid type detecting chamber is provided, the amountof stay of the fluid to be detected is increased. Therefore, the typeand concentration of the fluid to be detected can be accurately detectedwithout undergoing the influence of ambient environment such as externaltemperature.

Accordingly, when the present invention is applied, for example, tofluids such as automotive gasoline and light oils, upon stop of anautomobile, for example, due to waiting for a signal, a fuel pump can bestopped and the liquid type and concentration of the fluid to bedetected can be instantaneously detected. In this case, after thecompletion of the detection, the fuel pump can be started to again startthe automobile. Therefore, the detection is not an obstacle to thedriving of the automobile.

Further, the present invention is characterized in that said flowcontrol plate has a fluid inflow port confronted with a fluidintroduction port in said liquid type detecting chamber and a fluidoutflow port confronted with a fluid discharge port in said liquid typedetecting chamber.

According to the above construction, the fluid to be detected isreliably introduced, from the fluid introduction port in the liquid typedetecting chamber, into the flow control plate surrounded by the flowcontrol plate, through the fluid inflow port in the flow control plateand reliably enters the circumference of the liquid type detectingsensor located within the fluid control plate. As a result, the liquidtype and concentration of the fluid to be detected can be detected withthe liquid type detecting sensor.

After the detection of the liquid type and concentration of the fluid tobe detected with the liquid type detecting sensor, the fluid after thedetection can be reliably discharged from the liquid discharge port inthe liquid type detecting chamber through the fluid outflow port in theflow control plate. Therefore, the detection of the fluid to be detectedcan be successively carried out with good accuracy.

Further, in this detection, air mixed into the fluid to be detected canbe reliably discharged from the fluid discharge port in the liquid typedetecting chamber through the fluid outflow port in the flow controlplate. Therefore, air does not stay around the liquid type detectingsensor, and the influence on the detection can be prevented,contributing to accurate detection.

The present invention is characterized in that the fluid introductionport in said liquid type detecting chamber and the fluid inflow port insaid flow control plate are spaced from each other by a predetermineddistance, and

the fluid discharge port in said liquid type detecting chamber and thefluid outflow port in said flow control plate are spaced from each otherby a predetermined distance.

Since the fluid introduction port in the liquid type detecting chamberand the fluid inflow port in the flow control plate are spaced from eachother by a predetermined distance, air mixed into the fluid to bedetected is moved through the space toward the outside of the flowcontrol plate and is discharged to the outside of the liquid typedetecting chamber through the fluid discharge port.

Therefore, the air does not enter the inside of the flow control plate,and, thus, air does not stay around the liquid type detecting sensor.This can realize the prevention of the influence of air on the detectionand thus can contribute to accurate detection.

Even though air enters the inside of the flow control plate, this aircan be reliably discharged from the fluid discharge port in the liquidtype detecting chamber through the fluid outflow port in the flowcontrol plate. Therefore, the air does not stay around the liquid typedetecting sensor. This can realize the prevention of the influence ofair on the detection and thus can contribute to accurate detection.

Further, the present invention is characterized in that the side wall inthe vicinity of the fluid discharge port in said liquid type detectingchamber is provided in an approximately arc form.

Since the side wall in the vicinity of the fluid discharge port in theliquid type detecting chamber is provided in an approximately arc form,air mixed into the fluid to be detected is guided along theapproximately arc-shaped side wall in the liquid type detecting chamberto the fluid discharge port in the liquid type detecting chamber and isthen discharged.

Therefore, the air does not stay around the fluid discharge port in theliquid type detecting chamber and does not stay around the liquid typedetecting sensor. This can realize the prevention of the influence ofair on the detection and thus can contribute to accurate detection.

Further, the present invention is characterized in that said liquid typedetecting chamber is provided with an approximately circular tube sidewall, and the fluid introduction port and the fluid discharge port insaid liquid type detecting chamber are provided so as to confront saidside wall.

In such a construction, the liquid type detecting chamber has anapproximately circular tube-shaped side wall and the fluid introductionport and the fluid discharge port in the liquid type detecting chamberare provided so as to confront the side wall. Therefore, in the vicinityof the fluid introduction port in the liquid type detecting chamber, airwhich has entered through the fluid introduction port in the liquid typedetecting chamber is guided outward along the approximately arc-shapedside wall. Therefore, air does not enter the inside of the flow controlplate through the fluid inflow port in the flow control plate.

Further, in the vicinity of the fluid discharge port in the liquid typedetection chamber, the air mixed into the fluid to be detected is guidedinward along the approximately arc-shaped side wall toward the fluiddischarge port. Therefore, the air is guided to the fluid discharge portin the liquid type detecting chamber and is then discharged.

Therefore, the air does not stay around the fluid discharge port in theliquid type detecting chamber and does not stay around the liquid typedetecting sensor. This can realize the prevention of the influence ofair on the detection and thus can contribute to accurate detection.

Further, the present invention is characterized in that a heatinsulating member is interposed between said liquid type detectingapparatus body and said liquid type detecting chamber.

Since a heat insulating member is interposed between said liquid typedetecting apparatus body and said liquid type detecting chamber,external temperature, external vibration, and external noise such asexternal electromagnetic waves do not affect the fluid to be detectedwithin the liquid type detecting chamber and the liquid type detectingsensor. Therefore, the liquid type and concentration of the fluid can bealways detected with good accuracy.

For example, when the present invention is applied to the detection ofautomotive gasoline and light oils, the influence, on the detectingsensor, of the difference in temperature between winter and summer, thedifference in temperature derived from direct sunlight, snow and thelike, external noise such as electromagnetic waves, and, further,vibration during driving and impact caused, for example, by jumping ofstone, can be prevented by this heat insulating member. Therefore, theliquid type and concentration of the fluid can be always detected withgood accuracy.

The present invention is characterized in that: said liquid typedetecting sensor comprises:

-   -   a liquid type detecting sensor heater provided within said        liquid type detecting chamber, and    -   a liquid temperature sensor spaced by a given distance from said        liquid type detecting sensor heater and provided within said        liquid type detecting chamber,    -   said liquid type detecting sensor heater comprising a heater and        a liquid type detecting liquid temperature sensor provided in        the vicinity of said heater, and        -   in conducting any one of or both the detection of the type            of said fluid to be detected and the detection of the            concentration of said fluid to be detected,        -   a pulse voltage is applied to said liquid type detecting            sensor heater for a predetermined period of time to heat,        -   the fluid to be detected which temporarily stays within said            liquid type detecting chamber is heated with the heater, and        -   any one of or both the liquid type of the fluid and the            concentration of the fluid are detected, by a voltage output            difference V0, corresponding to a difference in temperature            between the initial temperature and the peak temperature of            said liquid type detecting liquid temperature sensor.

In the adoption of the above construction, what is required is only toapply a pulse voltage for a predetermined period of time. Therefore, thetype and concentration of a fluid such as gasoline can be detected in anaccurate and rapid manner by heating for a short period of time, and,further, without heating the fluid to a temperature at which the fluidignites.

Specifically, since the above construction utilizes a correlationbetween the kinematic viscosity of the fluid and the sensor output,utilizes natural convection, and one pulse applied voltage, the type andconcentration of the fluid can be detected in an accurate and rapidmanner.

Further, the present invention is characterized in that the voltageoutput difference V0 is the difference in voltage between an averageinitial voltage V1 determined by sampling the initial voltage before theapplication of said pulse voltage by a predetermined number of times andan average peak voltage V2 determined by sampling the peak voltage afterthe application of said pulse voltage by a predetermined number oftimes, that is,V0=V2−V1.

By such a construction, the voltage output difference V0 can beaccurately determined based on the average value of a predeterminednumber of times of sampling for one pulse applied voltage. Therefore,the type and concentration of a fluid can be detected in an accurate andrapid manner.

Further, the present invention is characterized in that any one of orboth the liquid type and concentration of said fluid to be detected aredetected using said voltage output difference V0 obtained for said fluidto be detected,

based on previously stored calibration curve data as a correlationbetween temperature and voltage output difference for predeterminedreference fluids.

According to the above construction, the type and concentration of thefluid are detected using the voltage output difference V0 obtained forthe fluid to be detected, based on previously stored calibration curvedata as a correlation between temperature and voltage output differencefor predetermined reference fluids. Therefore, the type andconcentration of a fluid can be detected in a more accurate and rapidmanner.

Further, the present invention is characterized in that:

a voltage output Vout for the voltage output difference V0 at ameasuring temperature for said fluid to be detected is corrected in acorrelation with the output voltage for the voltage output difference atthe measuring temperature for a predetermined threshold reference fluid.

By adopting such a construction, a voltage output Vout for the voltageoutput difference V0 at a measuring temperature for said fluid to bedetected is corrected in a correlation with the output voltage for thevoltage output difference at the measuring temperature for apredetermined threshold reference fluid. Therefore, the influence of thetemperature on the voltage output difference V0 can be eliminated toimpart a more accurate correlation between the voltage output Vout andthe properties of gasoline. As a result, the type and concentration ofthe fluid can be detected in a more accurate and rapid manner.

Further, the present invention is characterized in that said liquid typedetecting sensor heater is a laminated liquid type detecting sensorheater in which a heater and a liquid type detecting liquid temperaturesensor are laminated through an insulating layer.

By adopting such a construction, since any mechanically moved mechanismpart does not exist, malfunction derived from a deterioration with theelapse of time or the presence of foreign matter in the fluid or thelike does not occur. Consequently, the liquid type and concentration ofthe fluid can be detected in an accurate and rapid manner.

Furthermore, since the sensor part can be constructed in a very smallsize, the thermal response is very good and the liquid type andconcentration of the fluid can be accurately detected.

Furthermore, the present invention is characterized in that the heaterin said liquid type detecting sensor heater and said liquid typedetecting liquid temperature sensor each are constructed so as to comeinto contact with the fluid to be detected through a metallic fin.

According to the above construction, the heater of the liquid typedetecting sensor heater and the liquid type detecting liquid temperaturesensor do not come into direct contact with a fluid to be detected.Therefore, malfunction derived from a deterioration with the elapse oftime or the presence of foreign matter or the like in the fluid does notoccur. Consequently, the type and concentration of the fluid can bedetected in an accurate and rapid manner.

Furthermore, the present invention is characterized in that said liquidtemperature sensor is constructed so as to come into contact with thefluid to be detected through said metallic fin.

By adopting such a construction, the liquid temperature sensor does notcome into direct contact with a fluid to be detected. Therefore,malfunction derived from a deterioration with the elapse of time or thepresence of foreign matter or the like in the fluid does not occur.Consequently, the type and concentration of the fluid can be detected inan accurate and rapid manner.

The liquid type detecting apparatus for an automobile according to thepresent invention is adapted for the detection of the type of gasolineor a light oil, comprising;

-   -   the liquid type detecting apparatuses according to the present        invention, which is provided within a fuel tank or on the        upstream side or downstream side of a fuel pump.

The liquid type detecting method for an automobile according to thepresent invention is adapted for detecting the type of gasoline or alight oil, comprising:

-   -   detecting the type of said gasoline or light oil within a fuel        tank or on the upstream side or downstream side of a fuel pump,        by using any of the above liquid type detecting methods.

By adopting such a construction, in automobiles, the type of gasoline ora light oil can be detected in an accurate and rapid manner.

The automotive exhaust gas reduction apparatus according to the presentinvention is adapted for reducing an exhaust gas from an automobile,comprising:

-   -   any of the above liquid type detecting apparatuses, which is        provided within a fuel tank or on the upstream is side or        downstream side of a fuel pump; and    -   an ignition timing control unit for regulating ignition timing        based on the type of the gasoline or light oil, which is        detected by said liquid type detecting apparatus.

The automotive exhaust gas reduction method according to the presentinvention is adopted for reducing an exhaust gas from an automobile,comprising the steps of:

-   -   detecting the type of the gasoline or light oil within a fuel        tank or on the upstream side or downstream side of a fuel pump,        by using any of the above liquid type detecting methods, and    -   regulating an ignition timing based on the type of the gasoline        or light oil which is detected by said liquid type detecting        apparatus.

By adopting such a construction, ignition timing can be adjusted basedon the results of detection of the flow rate and the type of gasoline ora light oil. Therefore, proper ignition timing depending upon the typeof gasoline or a light oil can be provided.

Accordingly, in particular, even when an engine is started, particularlywhen an engine in which a catalyst device is not in a warmed state isstarted, the content of HCs and NOx in the exhaust gas can be reduced,and, at the same time, fuel consumption can be improved, without causinga reduction in torque.

The automotive exhaust gas reduction apparatus according to the presentinvention is adopted for reducing an exhaust gas from an automobile,comprising:

-   -   any of the above liquid type detecting apparatuses, which is        provided within a fuel tank or on the upstream side or        downstream side of a fuel pump; and    -   a gasoline or light oil compression control unit for regulating        the compression ratio of the gasoline or light oil based on the        type of the gasoline or light oil which is detected by said        liquid type detecting apparatus.

The automotive exhaust gas reduction method according to the presentinvention is adapted for reducing an exhaust gas from an automobile,comprising the steps of:

-   -   detecting the type of the gasoline or light oil within a fuel        tank or on the upstream side or downstream side of a fuel pump,        by using any of the above liquid type detecting methods, and    -   regulating the compression ratio of the gasoline based on the        type of the gasoline or light oil which is detected by said        liquid type detecting apparatus.

By adopting such a construction, the compression ratio of gasoline or alight oil can be adjusted based on the results of detection of the typeof gasoline or a light oil. Therefore, proper compression ratio ofgasoline or a light oil depending upon the type of gasoline can beprovided.

Accordingly, in particular, even when an engine is started, particularlywhen an engine in which a catalyst device is not in a warmed state isstarted, the content of HCs and NOx in the exhaust gas can be reduced.As a result, and, at the same time, fuel consumption can be improved,without causing a reduction in torque.

The automotive exhaust gas reduction apparatus according to the presentinvention is adopted for reducing an exhaust gas from an automobile,comprising:

-   -   a urea solution feed mechanism for feeding a urea solution to        the upstream side of a catalyst device,    -   said urea solution feed mechanism comprising a urea solution        tank for storing a urea solution, a urea pump, a urea spray        device for spraying the urea solution, which is supplied from        said urea pump, toward the upstream side of said catalyst        device, and    -   any of the above liquid type detecting apparatuses, which is        provided within said urea tank or on the upstream side or        downstream side of said urea pump.

The automotive exhaust gas reduction method according to the presentinvention is adapted for reducing an exhaust gas from an automobile,comprising the steps of:

-   -   supplying a urea solution to the upstream side of the catalyst        device, through a urea solution feed mechanism comprising a urea        solution tank for storing a urea solution, a urea pump, and a        urea spray device for spraying the urea solution, which is        supplied from said urea pump, toward the upstream side of said        catalyst device, and    -   detecting the urea concentration of the urea solution within        said urea tank or on the upstream side or downstream side of        said urea pump, by using any of the above liquid type detecting        methods.

According to the above construction, in order to efficiently cause areduction reaction on the upstream side of the catalyst device withoutcausing solidification of the urea solution, whether or not, forexample, the urea solution comprises 32.5% of urea and 67.5% of H₂O canbe judged in an accurate and rapid manner.

Therefore, the urea concentration of the urea solution in the urea tankcan be kept at a predetermined concentration, and, thus, the NOx in theexhaust gas can be decreased to a very low level by reduction.

EFFECT OF THE INVENTION

According to the above construction, in conducting any one of or boththe detection of the type of said fluid to be detected and the detectionof the concentration of said fluid to be detected, any one of or boththe detection of the liquid type and the detection of the concentrationcan be carried out in an accurate and rapid manner by closing theauxiliary passage opening/closing valve and allowing the fluid to bedetected to temporarily stay within said flow rate/liquid type detectingsensor device.

On the other hand, in detecting the flow rate of the fluid to bedetected, the flow rate can be detected by opening the auxiliary passageopening/closing valve and allowing the fluid to be detected to flow intothe flow rate/liquid type detecting sensor device.

Thus, the liquid type and concentration of a fluid can also be detectedsimultaneously with the detection of the flow rate of the fluid in anaccurate and rapid manner. Further, simultaneous detection of the flowrate of the fluid and the detection of the liquid type and concentrationof the fluid can be realized in a single flow rate/liquid type detectingapparatus. Therefore, detection in a compact manner can be realized,and, for example, when this is applied to an automotive system, thewhole system can be rendered compact.

Further, according to the present invention, the non-return valve isprovided on the downstream side of the flow rate/liquid type detectingsensor device in the auxiliary passage. Therefore, if backward flow iscaused, for example, due to the occurrence of pulsating flow dependingupon the type of a pump as a liquid feed device for the flow of a fluid,and the type of a drive system, this backward flow can be prevented.

Since the backward flow of the fluid within the flow rate/liquid typedetecting sensor device can be prevented, the detection of liquid type,the detection of concentration, and the detection of flow rate can becarried out in an accurate and rapid manner without undergoing theinfluence of backward flow of the fluid.

Further, according to the present invention, ehen the flow rate of thefluid to be detected is small, closing of the main passageopening/closing valve allows the fluid to be detected to flow into theauxiliary passage to ensure the flow rate of the fluid necessary for thedetection in the flow rate/liquid type detecting sensor device.

On the other hand, when the flow rate of the fluid to be detected islarge, opening of the main passage opening/closing valve allows thefluid to flow into the main passage to lower the flow rate of the fluidwhich flows into the auxiliary passage and thus to ensure the flow rateof the fluid necessary for the detection in the flow rate/liquid typedetecting sensor device.

Accordingly, the present invention can be utilized even when the dynamicrange of the flow rate is large, and, thus, it is possible to provide aflow rate/liquid type detecting apparatus and a flow rate/liquid typedetecting method with a wide sensitivity range.

Further, according to the present invention, since an orifice isprovided in the main passage, even when the pressure loss within themain passage is so small that the fluid is less likely to flow into theauxiliary passage, the pressure loss in the main passage can beincreased by the orifice. As a result, the fluid can be allowed to flowat a given flow rate necessary for detection into the auxiliary passageand, thus, the above detection can be reliably carried out.

Further, according to the present invention, in the case where theintroduction of the fluid to be detected into the liquid type detectingapparatus body is stopped to allow the fluid to be detected totemporarily stay within the liquid type detecting chamber, the flow ofthe fluid to be detected within the liquid type detecting chamber issuppressed by the flow control plate. As a result, the flow of the fluidto be detected around the liquid type detecting sensor, which is locatedwithin the flow control plate surrounded by this flow control plate, isinstantaneously stopped.

Therefore, in detecting the liquid type and concentration with theliquid type detecting sensor, the flow of the fluid to be detected doesnot occur, and, further, turbulence of the fluid to be detected by thevibration does not occur. Thus, the influence on the detection of theliquid type and concentration of the fluid to be detected can beprevented. Consequently, the liquid type and concentration of the fluidto be detected can be accurately measured.

Further, since a liquid type detecting chamber is provided, the amountof stay of the fluid to be detected is increased. Therefore, the typeand concentration of the fluid to be detected can be accurately detectedwithout undergoing the influence of ambient environment such as externaltemperature.

Accordingly, when the present invention is applied, for example, tofluids such as automotive gasoline and light oils, upon stop of anautomobile, for example, due to waiting for a signal, a fuel pump can bestopped and the liquid type and concentration of the fluid to bedetected can be instantaneously detected. In this case, after thecompletion of the detection, the fuel pump can be started to again startthe automobile. Therefore, the detection is not an obstacle to thedriving of the automobile.

Further, according to the present invention, the fluid to be detected isreliably introduced, from the fluid introduction port in the liquid typedetecting chamber, into the flow control plate surrounded by the flowcontrol plate, through the fluid inflow port in the flow control plateand reliably enters the circumference of the liquid type detectingsensor located within the fluid control plate. As a result, the liquidtype and concentration of the fluid to be detected can be detected withthe liquid type detecting sensor.

After the detection of the liquid type and concentration of the fluid tobe detected with the liquid type detecting sensor, the fluid after thedetection can be reliably discharged from the liquid discharge port inthe liquid type detecting chamber through the fluid outflow port in theflow control plate. Therefore, the detection of the fluid to be detectedcan be successively carried out with good accuracy.

Further, in this detection, air mixed into the fluid to be detected canbe reliably discharged from the fluid discharge port in the liquid typedetecting chamber through the fluid outflow port in the flow controlplate. Therefore, air does not stay around the liquid type detectingsensor, and the influence on the detection can be prevented,contributing to accurate detection.

Further, according to the present invention, since the fluidintroduction port in the liquid type detecting chamber and the fluidinflow port in the flow control plate are spaced from each other by apredetermined distance, air mixed into the fluid to be detected is movedthrough the space toward the outside of the flow control plate and isdischarged to the outside of the liquid type detecting chamber throughthe fluid discharge port.

Therefore, the air does not enter the inside of the flow control plate,and, thus, air does not stay around the liquid type detecting sensor.This can realize the prevention of the influence of air on the detectionand thus can contribute to accurate detection.

Even though air enters the inside of the flow control plate, this aircan be reliably discharged from the fluid discharge port in the liquidtype detecting chamber through the fluid outflow port in the flowcontrol plate. Therefore, the air does not stay around the liquid typedetecting sensor. This can realize the prevention of the influence ofair on the detection and thus can contribute to accurate detection.

Further, according to the present invention, since the side wall in thevicinity of the fluid discharge port in the liquid type detectingchamber is provided in an approximately arc form, air mixed into thefluid to be detected is guided along the approximately arc-shaped sidewall in the liquid type detecting chamber to the fluid discharge port inthe liquid type detecting chamber and is then discharged.

Therefore, the air does not stay around the fluid discharge port in theliquid type detecting chamber and does not stay around the liquid typedetecting sensor. This can realize the prevention of the influence ofair on the detection and thus can contribute to accurate detection.

Further, according to the present invention, the liquid type detectingchamber has an approximately circular tube-shaped side wall and thefluid introduction port and the fluid discharge port in the liquid typedetecting chamber are provided so as to confront the side wall.Therefore, in the vicinity of the fluid introduction port in the liquidtype detecting chamber, air which has entered through the fluidintroduction port in the liquid type detecting chamber is guided outwardalong the approximately arc-shaped side wall. Therefore, air does notenter the inside of the flow control plate through the fluid inflow portin the flow control plate.

Further, in the vicinity of the fluid discharge port in the liquid typedetection chamber, the air mixed into the fluid to be detected is guidedinward along the approximately arc-shaped side wall toward the fluiddischarge port. Therefore, the air is guided to the fluid discharge portin the liquid type detecting chamber and is then discharged.

Therefore, the air does not stay around the fluid discharge port in theliquid type detecting chamber and does not stay around the liquid typedetecting sensor. This can realize the prevention of the influence ofair on the detection and thus can contribute to accurate detection.

Further, according to the present invention, since a heat insulatingmember is interposed between said liquid type detecting apparatus bodyand said liquid type detecting chamber, external temperature, externalvibration, and external noise such as external electromagnetic waves donot affect the fluid to be detected within the liquid type detectingchamber and the liquid type detecting sensor. Therefore, the liquid typeand concentration of the fluid can be always detected with goodaccuracy.

For example, when the present invention is applied to the detection ofautomotive gasoline and light oils, the influence, on the detectingsensor, of the difference in temperature between winter and summer, thedifference in temperature derived from direct sunlight, snow and thelike, external noise such as electromagnetic waves, and, further,vibration during driving and impact caused, for example, by jumping ofstone, can be prevented by this heat insulating member. Therefore, theliquid type and concentration of the fluid can be always detected withgood accuracy.

Further, according to the present invention, what is required is only toapply a pulse voltage for a predetermined period of time. Therefore, thetype and concentration of a fluid such as gasoline can be detected in anaccurate and rapid manner by heating for a short period of time, and,further, without heating the fluid to a temperature at which the fluidignites.

Specifically, since the above construction utilizes a correlationbetween the kinematic viscosity of the fluid and the sensor output,utilizes natural convection, and one pulse applied voltage, the type andconcentration of the fluid can be detected in an accurate and rapidmanner.

Further, according to the present invention, the voltage outputdifference V0 can be accurately determined based on the average value ofa predetermined number of times of sampling for one pulse appliedvoltage. Therefore, the type and concentration of a fluid can bedetected in an accurate and rapid manner.

Further, according to the present invention, the type and concentrationof the fluid are detected using the voltage output difference V0obtained for the fluid to be detected, based on previously storedcalibration curve data as a correlation between temperature and voltageoutput difference for predetermined reference fluids. Therefore, thetype and concentration of a fluid can be detected in a more accurate andrapid manner.

Further, according to the present invention, a voltage output Vout forthe voltage output difference V0 at a measuring temperature for saidfluid to be detected is corrected in a correlation with the outputvoltage for the voltage output difference at the measuring temperaturefor a predetermined threshold reference fluid. Therefore, the influenceof the temperature on the voltage output difference V0 can be eliminatedto impart a more accurate correlation between the voltage output Voutand the properties of gasoline. As a result, the type and concentrationof the fluid can be detected in a more accurate and rapid manner.

Further, according to the present invention, since the flow rate/liquidtype detecting sensor heater is a laminated flow rate/liquid typedetecting sensor heater in which a heater and a flow rate/liquid typedetecting liquid temperature sensor are laminated through an insulatinglayer, any mechanically moved mechanism part does not exist. Therefore,malfunction derived from a deterioration with the elapse of time or thepresence of foreign matter in the fluid or the like does not occur.Consequently, the liquid type, concentration, and flow rate of the fluidcan be detected in an accurate and rapid manner.

Furthermore, since the sensor part can be constructed in a very smallsize, the thermal response is very good and the liquid type andconcentration of the fluid can be accurately detected.

Further, according to the present invention, the heater in said liquidtype detecting sensor heater and said liquid type detecting liquidtemperature sensor each are constructed so as to come into contact withthe fluid to be detected through a metallic fin. Therefore, the heaterof the liquid type detecting sensor heater and the liquid type detectingliquid temperature sensor do not come into direct contact with a fluidto be detected. Therefore, malfunction derived from a deterioration withthe elapse of time or the presence of foreign matter or the like in thefluid does not occur. Consequently, the type and concentration of thefluid can be detected in an accurate and rapid manner.

Further, according to the present invention, the liquid temperaturesensor is constructed so as to come into contact with the fluid to bedetected through a metallic fin. Therefore, the liquid temperaturesensor does not come into direct contact with a fluid to be detected.Therefore, malfunction derived from a deterioration with the elapse oftime or the presence of foreign matter or the like in the fluid does notoccur. Consequently, the type and concentration of the fluid can bedetected in an accurate and rapid manner.

Further, according to the present invention, in automobiles, the flowrate and type of gasoline or a light oil can be detected in an accurateand rapid manner, and, in addition, ignition timing can be adjustedbased on the results of the detection of the flow rate and type of thegasoline or light oil. Therefore, proper ignition timing depending uponthe flow rate and type of gasoline or a light oil can be realized.

Further, according to the present invention, in automobiles, the flowrate and type of gasoline or a light oil can be detected in an accurateand rapid manner, and, in addition, the compression ratio of thegasoline can be adjusted based on the results of the detection of theflow rate and type of the gasoline or light oil, proper compressionratio of gasoline or a light oil depending upon the flow rate and typeof gasoline or a light oil can be realized.

Accordingly, in particular, even when an engine is started, particularlywhen an engine in which a catalyst device is not in a warmed state isstarted, the content of HCs and NOx in the exhaust gas can be reduced.As a result, and, at the same time, fuel consumption can be improved,without causing a reduction in torque.

Further, according to the present invention, in order to efficientlycause a reduction reaction on the upstream side of the catalyst devicewithout causing solidification of the urea solution, whether or not, forexample, the urea solution comprises 32.5% of urea and 67.5% of H₂O canbe judged in an accurate and rapid manner.

Therefore, the urea concentration of the urea solution in the urea tankcan be kept at a predetermined concentration, and, thus, the NOx in theexhaust gas can be decreased to a very low level by reduction. Thus, thepresent invention is an excellent invention which has varioussignificant and inherent function and effect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing an embodiment of a flowrate/liquid type detecting apparatus according to the present invention;

FIG. 2 is a schematic top view showing an embodiment of a flowrate/liquid type detecting sensor device in a flow rate/liquid typedetecting apparatus according to the present invention;

FIG. 3 is a cross-sectional view taken on line A-A of FIG. 2;

FIG. 4 is a partially enlarged cross-sectional view showing the mountedstate of the flow rate/liquid type detecting sensor shown in FIG. 3;

FIG. 5 is a cross-sectional view of a flow rate/liquid type detectingsensor;

FIG. 6 is a partially enlarged exploded perspective view showing thestate of stacking of a thin-film chip part in a flow rate/liquid typedetecting sensor;

FIG. 7 is a schematic circuit block diagram of an embodiment of a flowrate/liquid type detecting sensor device in a flow rate/liquid typedetecting apparatus according to the present invention;

FIG. 8 is a graph showing a time vs. voltage relationship illustrating aliquid type detecting method using a flow rate/liquid type detectingapparatus according to the present invention;

FIG. 9 is a graph showing calibration curve illustrating a liquid typedetecting method using a flow rate/liquid type detecting apparatusaccording to the present invention;

FIG. 10 is a graph illustrating an output correction method in a liquidtype detecting method using a flow rate/liquid type detecting apparatusaccording to the present invention;

FIG. 11 is a graph showing a calibration curve illustrating a flow ratedetecting method using a flow rate/liquid type detecting apparatusaccording to the present invention;

FIG. 12 is a schematic diagram of the whole measuring apparatus used forobtaining calibration curve data shown in FIG. 11;

FIG. 13 is a graph showing a calibration curve illustrating aconcentration detecting method using a flow rate/liquid type detectingapparatus according to the present invention;

FIG. 14 is the same schematic diagram as FIG. 17, illustrating anembodiment in which a flow rate/liquid type detecting apparatus 1 havingthe above construction is applied to an automotive system;

FIG. 15 is the same schematic diagram as FIG. 17, illustrating anembodiment in which a flow rate/liquid type detecting apparatus 1 havingthe above construction is applied to an automotive system;

FIG. 16 is the same schematic diagram as FIG. 19, illustrating anembodiment in which a flow rate/liquid type detecting apparatus 1 havingthe above construction is applied to an automotive system using a ureasolution;

FIG. 17 is a schematic diagram of a conventional automotive system;

FIG. 18 is a graph showing distillation properties of gasoline;

FIG. 19 is a schematic diagram of a conventional automotive system usinga urea solution;

FIG. 20 is an exploded perspective view of the whole liquid typedetecting apparatus according to the present invention;

FIG. 21 is an exploded perspective view of a liquid type detectingchamber in a liquid type detecting apparatus according to the presentinvention;

FIG. 22 is a schematic diagram illustrating the state of detection of aliquid type detecting chamber in a liquid type detecting apparatusaccording to the present invention; and

FIG. 23 is a perspective view showing another embodiment of a liquidtype detecting apparatus according to the present invention.

DESCRIPTION OF THE INVENTION

The mode for carrying out the invention (embodiments) will be describedin more detail in conjunction with the accompanying drawings.

In FIG. 1, numeral 1 designates a flow rate/liquid type detectingapparatus as a whole. The flow rate/liquid type detecting apparatus 1comprises a main passage 2 through which, for example, a fluid to bedetected such as gasoline, a light oil, or a urea solution flows. Anauxiliary passage 3 is branched from the main passage 2.

A flow rate/liquid type detecting sensor device 10 is provided in theauxiliary passage 3, and an auxiliary passage opening/closing valve 5for controlling the flow of the fluid to be detected into the flowrate/liquid type detecting sensor device 10 is provided on the upstreamside of the flow rate/liquid type detecting sensor device 10. Further,in the auxiliary passage 3, a non-return valve 6 is provided on thedownstream side of the flow rate/liquid type detecting sensor device 10.

On the other hand, a main passage opening/closing valve 7 forcontrolling the flow of the fluid to be detected into the main passageis provided in the main passage 2, and an orifice 8 is provided on thedownstream side of the main passage opening/closing valve 7.

Further, a sensor control unit 9 comprising a communication device forcontrolling the flow rate/liquid type detecting sensor device 10, theauxiliary passage opening/closing valve 5, and the main passageopening/closing valve 7 is provided. When the flow rate/liquid typedetecting apparatus is applied to automobiles, ECU (an engine controlunit) 4 is connected to the sensor control unit 9.

In this case, the auxiliary passage opening/closing valve 5 and the mainpassage opening/closing valve 7 are not particularly limited, and forexample, a solenoid valve may be used.

The orifice 8 is also not particularly limited, and, for example, aflange tap orifice, a variable orifice, and an orifice with a pluralityof capillaries can be adopted.

The flow rate/liquid type detecting apparatus 1 having the aboveconstruction is operated as follows.

In conducting any one of or both the detection of the type of the fluidto be detected and the detection of the concentration of the fluid to bedetected, control is carried out by the sensor control unit 9 (or ECU 4)in such a manner that, after opening the auxiliary passageopening/closing valve 5, the auxiliary passage opening/closing valve 5is closed to allow the fluid to be detected to temporarily stay withinthe flow rate/liquid type detecting sensor device 10 and to conduct anyone of or both the detection of the liquid type and the detection of theconcentration.

On the other hand, in detecting the flow rate of the fluid to bedetected, control is carried out by the sensor control unit 9 (or ECU 4)in such a manner that the auxiliary passage opening/closing valve 5 isopened to allow the fluid to be detected to flow into the flowrate/liquid type detecting sensor device 10 and, in this state, the flowrate is detected.

The sensor control unit 9 (or ECU 4) is constructed so that, in thiscase, control is carried out in such a manner that, when the flow rateof the fluid to be detected is small, the main passage opening/closingvalve 7 is closed, while, when the flow rate of said fluid to bedetected is large, the main passage opening/closing valve 7 is opened.

That is to say, where the flow rate of the fluid to be detected issmall, the main passage opening/closing valve 7 is closed. As a result,he fluid to be detected is flew into the auxiliary passage 3 so that theflow rate of the fluid necessary for the detection in the flowrate/liquid type detecting sensor device 10 can be ensured.

On the other hand, where the flow rate of the fluid to be detected islarge, the main passage opening/closing valve 7 is opened so that thefluid is flew into the main passage 2, so that the flow rate of thefluid which flows into the auxiliary passage 3 is lowered. As a result,the flow rate of the fluid necessary for the detection in the flowrate/liquid type detecting sensor device 10 can be ensured.

Accordingly, the present invention can be utilized even when the dynamicrange of the flow rate is large, and, thus, the sensitivity range can bebroadened.

The provision of the non-return valve 6 on the downstream side of theflow rate/liquid type detecting sensor device 10 in the auxiliarypassage 3 can prevent backward flow caused, for example, due to theoccurrence of pulsating flow depending upon the type of a pump as aliquid feed device for the flow of a fluid, and the type of a drivesystem.

Since the backward flow within the flow rate/liquid type detectingsensor device 10 can be prevented, the detection of liquid type, thedetection of concentration, and the detection of flow rate can becarried out in an accurate and rapid manner without undergoing theinfluence of backward flow of the fluid.

Since an orifice 8 is provided in the main passage 2, even when thepressure loss within the main passage 2 is so small that the fluid isless likely to flow into the auxiliary passage 3, the pressure loss inthe main passage 2 can be increased by the orifice 8. As a result, thefluid can be allowed to flow at a given flow rate necessary fordetection into the auxiliary passage 3 and, thus, the above detectioncan be reliably carried out.

The flow rate/liquid type detecting sensor device 10 used in the flowrate/liquid type detecting apparatus 1 according to the presentinvention will be described.

As shown in FIGS. 2 and 3, the flow rate/liquid type detecting sensordevice 10 according to the present invention comprises a flowrate/liquid type detecting sensor device body 12 and a first passage 14and a second passage 16 provided within the flow rate/liquid typedetecting sensor device body 12.

As indicated by an arrow shown in FIG. 2, a fluid is introduced througha fluid introduction port 18, is passed through a first passage 14, andtemporarily stays within a flow rate/liquid type detecting chamber 20.In this flow rate/liquid type detecting chamber 20, a substantiallytrack-shaped flow rate/liquid type detecting sensor opening part 22 isprovided on its upper part.

As shown in FIG. 3, a flow rate/liquid type detecting sensor 24 ismounted in the flow rate/liquid type detecting sensor opening part 22.

As shown in FIG. 4, the flow rate/liquid type detecting sensor 24comprises a flow rate/liquid type detecting sensor heater 25 and aliquid temperature sensor 28 disposed by a given distance from the flowrate/liquid type detecting sensor heater 25. The flow rate/liquid typedetecting sensor heater 25 and the liquid temperature sensor 28 areformed integrally with a mold resin 30.

Further, as shown in FIG. 5, the flow rate/liquid type detecting sensorheater 25 comprises lead electrodes 32 and a thin-film chip part 34. Inthe flow rate/liquid type detecting sensor heater 25, metallic fins 36are provided. The metallic fins 36 are protruded from the mold resin 30into the flow rate/liquid type detecting chamber 20 through the openingpart 22 for a flow rate/liquid type detecting sensor so as to come intodirect contact with the fluid to be detected. These lead electrodes 32,thin-film chip part 34, and fins 36 are electrically connected to eachother through a bonding wire 38.

On the other hand, the liquid temperature sensor 28 has the sameconstruction as the flow rate/liquid type detecting sensor heater 25 andcomprises a lead electrode 32, a thin-film chip part 34, fins 36 and abonding wire 38.

As shown in FIG. 6, the thin-film chip part 34 comprises a thin-filmchip comprising, for example, a substrate 40 formed of Al₂O₃, atemperature sensor (a temperature detector) 42 formed of Pt, aninterlayer insulation film 44 formed of SiO₂, a heater (a heatingelement) 46 formed of TaSiO₂, a heating element electrode 48 formed ofNi, a protective film 50 formed of SiO₂, and an electrode pad 52 formedof Ti/Au stacked in that order.

The thin-film chip part 34 in the liquid temperature sensor 28 also hasthe same structure, except that only the temperature sensor (temperaturedetector) 42 is allowed to act without allowing the heater (heatingelement) 46 to act.

After the liquid type, concentration, and flow rate of the fluid to bedetected are detected with this flow rate/liquid type detecting sensor24, the detected fluid is discharged from a flow rate/liquid typedetecting chamber 20, is passed through a second passage 16, and isdischarged into the outside of the apparatus through a fluid dischargeport 54.

In FIGS. 2 and 3, a circuit substrate member connected to the flowrate/liquid type detecting sensor 24 and a lid member covering this areomitted.

In the flow rate/liquid type detecting sensor device 10 according to thepresent invention, the circuit construction is as shown in FIG. 7.

In FIG. 7, a flow rate/liquid type detecting liquid temperature sensor26 in a flow rate/liquid type detecting sensor heater 25 of a flowrate/liquid type detecting sensor 24 is connected to a liquidtemperature sensor 28 through two resistors 64, 66 to constitute abridge circuit 68. The output of the bridge circuit 68 is connected tothe input of an amplifier 70. The output of this amplifier 70 isconnected to the input of a computer 72 constituting a detecting controlunit.

A heater 74 in the flow rate/liquid type detecting sensor heater 25 isconstructed so that the applied voltage is controlled by the control ofthe computer 72.

In the flow rate/liquid type detecting sensor device 10 having the aboveconstruction, for example, the liquid type of gasoline is detected asfollows.

First of all, control is carried out by the sensor control unit 9 (orECU 4) in such a manner that, after the auxiliary passageopening/closing valve 5 is opened, the auxiliary passage opening/closingvalve 5 is closed. As a result, the fluid to be detected flows into theflow rate/liquid type detecting chamber 20 through the fluidintroduction port 18 in the first passage 14 in the flow rate/liquidtype detecting sensor device 10. Consequently, the fluid is temporarilystayed within the flow rate/liquid type detecting chamber 20.

As shown in FIGS. 7 and 8, a pulse voltage P is applied to the heater 74in the flow rate/liquid type detecting sensor heater 25 for apredetermined period of time, for example, for 4 sec in the case of thisembodiment, by controlling the computer 72. Moreover, a change intemperature of the analog output of a sensing part, that is, a sensorbridge circuit 68 is measured as shown in FIG. 7.

That is, as shown in FIG. 8, a voltage difference in a sensor bridgecircuit 68 before the application of a pulse voltage P to the heater 74in the flow rate/liquid type detecting sensor heater 25 is sampled apredetermined number of times in one sec, for example, 256 times in thecase of this embodiment. As a result, and the average value thereof isdetermined as an average initial voltage V1. The value of the averageinitial voltage V1 corresponds to the initial temperature of the flowrate/liquid type detecting liquid temperature sensor 26.

Thereafter, as shown in FIG. 8, a predetermined pulse voltage P (in thisembodiment, a voltage of 10 V for 4 sec) is applied to the heater 74 inthe flow rate/liquid type detecting sensor heater 25. Next, after apredetermined period of time (in this embodiment, after 3 sec), the peakvoltage is sampled a predetermined number of times (in this embodiment,256 times for one sec), and the average of sampled data is determined asan average peak voltage V2. This average peak voltage V2 corresponds toa peak temperature of the flow rate/liquid type detecting liquidtemperature sensor 26.

An voltage output difference V0 is obtained from the voltage differencebetween an average initial voltage V1 and an average peak voltage V2,that is,V0=V2−V1.

Specifically, in this way, as shown in FIG. 9, for predeterminedreference fluids, for example, for the heaviest (difficult to evaporate)gasoline A2 and the lightest (easy to evaporate) gasoline No. 7 in thisembodiment, calibration curve data for a temperature vs. voltage outputdifference correlation are previously obtained and are stored in thecomputer 72 constituting the control unit.

Thereafter, a proportional calculation is carried out with the computer72 based on the calibration curve data. As a result, and the type of thegasoline is detected based on the voltage output difference V0 obtainedfor the fluid to be detected.

Specifically, as shown in FIG. 10, the voltage output Vout for thevoltage output difference V0 at the measuring temperature T of the fluidto be detected is correlated with the output voltage for the voltageoutput difference at the measuring temperature for a predeterminedthreshold reference fluid (in this embodiment, gasoline A2 and gasolineNo. 7) for correction.

Specifically, as shown in FIG. 10 (A), based on the calibration curvedata, at a temperature T, the voltage output difference V0−A2 forgasoline A2, the voltage output difference V0−7 for gasoline No. 7, andthe voltage output difference V0−S for the fluid to be detected areobtained.

As shown in FIG. 10 (B), a correlation with the properties of gasolinecan be established by bringing the liquid type output of the thresholdreference fluid in this case to a predetermined voltage, that is, by, inthis embodiment, bringing the liquid type output of gasoline A2 to 3.5 Vand bringing the liquid type output of gasoline No. 7 to 0.5 V, andobtaining the voltage output Vout of the fluid to be detected.

The liquid type of gasoline can be detected in an accurate and rapid(instantaneous) manner by comparing the voltage output Vout of the fluidto be detected with the data previously stored in the computer 72 basedon the calibration curve data.

In the above case, regarding the pulse width (pulse application time),in case of the detection of liquid type and the detection ofconconcentration, since the fluid to be detected stays, avoidingoverheating is prefered. For this reason, the pulse width is preferablyless than 5 sec. On the other hand, in the case of the detection of flowrate, the fluid to be detected does not stay. Therefore, the flow ratecan be detected when the pulse width (pulse application time) is notless than 1 sec.

The above liquid type detecting method for gasoline utilize naturalconvection and utilizes such a principle that the kinematic viscosity ofgasoline has a correlation with the sensor output.

Further, regarding the flow rate/liquid type detecting method forgasoline, in the distillation properties of gasoline shown in FIG. 18,distillation properties T30 to T70 have been found to provide a bettercorrelation and thus are preferred.

On the other hand, in the flow rate/liquid type detecting sensor device10, for example, the detection of the flow rate of gasoline is carriedout as follows. In detecting the flow rate of the fluid to be detected,by controlling of the sensor control unit 9 (or ECU 4), the auxiliarypassage opening/closing valve 5 is opened and the fluid to be detectedflows into the flow rate/liquid type detecting sensor device 10 throughthe fluid introduction port 18 in the first passage 14 of the flowrate/liquid type detecting sensor device 10. Thereafter, the introducedfluid is discharged from the flow rate/liquid type detecting chamber 20,is passed through the second passage 16 and is discharged through thefluid discharge port 54 into the outside of the apparatus. As a result,the fluid to be detected is such a state that the fluid is allowed toflow into the flow rate/liquid type detecting sensor device 10.

In this state, as with the detection of the liquid type, a voltageoutput Vout of the fluid to be detected is obtained, and the flow rateof gasoline can be detected in an accurate and rapid (instantaneous)manner by comparing voltage output Vout of the fluid to be detected withthe data stored in the computer 72 based on previously measuredcalibration curve data for flow rate as shown in FIG. 11.

The calibration curve data shown in FIG. 11 are an example of theresults of measurement for commercially available high-octane gasolinewith a commercially available flow meter in a measuring apparatus asshown in FIG. 12.

In this case, the flow rate is 0 to 180 liters/hr, and the measurementin the flow rate/liquid type detecting sensor device 10 is carried outunder conditions of a pulse time of 3 to 5 sec, preferably 4 sec, apulse voltage of 10 V (corresponding to 250 mV), a pulse applicationtime of 5 to 12 sec, and a temperature of 0 to 80° C.

Further, when the concentration of the fluid to be detected is measured,for example, in the case of an identification urea solution, as with thedetection of the liquid type, the voltage output Vout can be obtainedand correlated with the properties of urea.

The content of urea in the urea solution can be identified in anaccurate and rapid (instantaneous) manner by comparing the voltageoutput Vout of the urea solution to be identified with data stored inthe computer 72 based on previously measured calibration data for a ureasolution as shown in FIG. 13.

In FIG. 1, numeral 10 designates a liquid type detecting apparatusaccording to the present invention as a whole. The liquid type detectingapparatus 10 comprises an approximately box-shaped liquid type detectingapparatus body 12 through which a fluid to be detected such as gasoline,a light oil, or a urea solution flows.

FIG. 20 is an exploded perspective view of the whole liquid typedetecting apparatus according to the present invention, and FIG. 21 anexploded perspective view of a liquid type detecting chamber in theliquid type detecting apparatus according to the present invention.

The liquid type detecting apparatus in this embodiment basically usesthe same constituent members as used in the flow rate/liquid typedetecting sensor device 10 shown in FIGS. 3 to 10. Accordingly, theliquid type detecting apparatus will be described in detail whilechanging the term “flow rate/liquid type detecting” in the flowrate/liquid type detecting sensor device 10 shown in FIGS. 3 to 10 tothe term “liquid type detecting”.

As shown in FIG. 20, an approximately circular tube-shaped liquid typedetecting chamber 20 is provided within a liquid type detectingapparatus body 12 in this apparatus. Further, a first passage 14 and asecond passage 16 are provided in the liquid type detecting apparatusbody 12.

The first passage 14 is connected to a fluid introduction port 18provided in the liquid type detecting chamber 20. The second passage 16is connected to a fluid discharge port 11 provided in the liquid typedetecting chamber 20.

The liquid type detecting apparatus is constructed so that, as indicatedby an arrow in FIG. 21, the fluid to be detected introduced into theliquid type detecting apparatus body 12 is introduced from the firstpassage 14 through the fluid introduction port 18 into the liquid typedetecting chamber 20 where the fluid temporarily stays.

A lid member 21 for a liquid type detecting chamber is mounted on theupper part of the liquid type detecting chamber 20. An approximatelytrack-shaped opening 22 for a liquid type detecting sensor is providedin the lid member 21 for a liquid type detecting chamber.

As shown in FIG. 3, a liquid type detecting sensor 24 is mounted in theliquid type detecting sensor opening part 22.

As shown in FIG. 4, the liquid type detecting sensor 24 comprises aliquid type detecting sensor heater 25 and a liquid temperature sensor28 disposed by a given distance from the liquid type detecting sensorheater 25. The liquid type detecting sensor heater 25 and the liquidtemperature sensor 28 are formed integrally with a mold resin 30.

Further, as shown in FIG. 5, the liquid type detecting sensor heater 25comprises lead electrodes 32 and a thin-film chip part 34. In the liquidtype detecting sensor heater 25, metallic fins 36 are provided. Themetallic fins 36 are protruded from the mold resin 30 into the liquidtype detecting chamber 20 through the opening part 22 for a liquid typedetecting sensor so as to come into direct contact with the fluid to bedetected. These lead electrodes 32, thin-film chip part 34, and fins 36are electrically connected to each other through a bonding wire 38.

On the other hand, the liquid temperature sensor 28 has the sameconstruction as the liquid type detecting sensor heater 25 and comprisesa lead electrode 32, a thin-film chip part 34, fins 36 and a bondingwire 38.

As shown in FIG. 6, the thin-film chip part 34 comprises a thin-filmchip comprising, for example, a substrate 40 formed of Al₂O₃, atemperature sensor (a temperature detector) 42 formed of Pt, aninterlayer insulation film 44 formed of SiO₂, a heater (a heatingelement) 46 formed of TaSiO₂, a heating element electrode 48 formed ofNi, a protective film 50 formed of SiO₂, and an electrode pad 52 formedof Ti/Au stacked in that order.

The thin-film chip part 34 in the liquid temperature sensor 28 also hasthe same structure, except that only the temperature sensor (temperaturedetector) 42 is allowed to act without allowing the heater (heatingelement) 46 to act.

After the liquid type and concentration of the fluid to be detected aredetected with this liquid type detecting sensor 24, the detected fluidis discharged from a liquid type detecting chamber 20, is passed througha second passage 16 through a fluid discharge port 11 in the liquid typedetecting chamber 20, and is discharged into the outside of theapparatus.

Further, as shown in FIG. 20, the liquid type detecting sensor 24 isprovided with a circuit board member 23 and an outer lid member 27covering the circuit board member 23. In FIGS. 21 and 3, the circuitboard member 23 and the outer lid member 27 are not shown for theconvenience of explanation.

In FIG. 20, reference characters 12 a, 12 b each designate amountingflange for mounting the liquid type detecting apparatus 10 provided inthe liquid type detecting apparatus body 12, for example, onautomobiles.

On the other hand, as shown in FIG. 21, a flow control plate 80 isprovided on the inner side of the lid member 21 for a liquid typedetecting chamber so that the flow control plate 80 surrounds a liquidtype detecting sensor 24, which is provided so as to be protruded intothe liquid type detecting chamber 20.

This flow control plate 80 is formed of a plate member 82 of asubstantially U shape in section. This plate member 82 comprises a pairof side plate members 84, 86, which surrounds the liquid type detectingsensor 24 from both sides thereof and extends from the fluidintroduction port 18 in the liquid type detecting chamber 20 toward thefluid discharge port 11. Moreover, this plate member 82 comprises acovering plate member 88 connected to these side plate members 84, 86.

The flow control plate 80 has a fluid inflow port 90 which confronts thefluid introduction port 18 in the liquid type detecting chamber 20 and afluid outflow port 92 which confronts the fluid discharge port 11 in theliquid type detecting chamber 20.

The fluid introduction port 18 in the liquid type detecting chamber 20and the fluid inflow port 90 in the flow control plate 80 are spacedfrom each other by a predetermined distance L1. Moreover, the fluiddischarge port 11 in the liquid type detecting chamber 20 and the fluidoutflow port 92 in the flow control plate 80 are spaced from each otherby a predetermined distance L2.

According to the above construction, in the case where the introductionof the fluid to be detected into the liquid type detecting apparatusbody 12 is stopped to allow the fluid to be detected to temporarily staywithin the liquid type detecting chamber 20, the flow of the fluid to bedetected within the liquid type detecting chamber 20 is suppressed bythe flow control plate 80. Consequently, the flow of the fluid to bedetected around the liquid type detecting sensor 24, which is locatedwithin and surrounded by the flow control plate 80 is instantaneouslystopped.

Specifically, the fluid to be detected is reliably introduced, from thefluid introduction port 18 in the liquid type detecting chamber 20, intothe flow control plate 80 surrounded by the flow control plate 80,through the fluid inflow port 90 in the flow control plate 80. As aresult, the fluid to be detected is reliably entered around thecircumference of the liquid type detecting sensor 24 which is locatedwithin the fluid control plate 80, so that the liquid type andconcentration of the fluid to be detected can be detected with theliquid type detecting sensor 24.

After the liquid type and concentration of the fluid to be detected isdetected with the liquid type detecting sensor 24, the fluid after thedetection can be reliably discharged from the liquid discharge port 11in the liquid type detecting chamber 20 through the fluid outflow port92 in the flow control plate 80. Therefore, the detection of the fluidto be detected can be successively carried out with good accuracy.

Therefore, in detecting the liquid type and concentration with theliquid type detecting sensor 24, the flow of the fluid to be detecteddoes not occur, and, further, turbulence of the fluid to be detected bythe vibration does not occur. Thus, the influence on the detection ofthe liquid type and concentration of the fluid to be detected can beprevented, and the liquid type and concentration of the fluid to bedetected can be accurately measured.

Further, since a liquid type detecting chamber 20 is provided, theamount of stay of the fluid to be detected is increased. Therefore, thetype and concentration of the fluid to be detected can be accuratelydetected without undergoing the influence of ambient environment such asexternal temperature.

Accordingly, when the present invention is applied, for example, tofluids such as automotive gasoline and light oils, upon stop of anautomobile, for example, due to waiting for a signal, a fuel pump can bestopped and the liquid type and concentration of the fluid to bedetected can be instantaneously detected. In this case, after thecompletion of the detection, the fuel pump can be started to again startthe automobile. Therefore, the detection is not an obstacle to thedriving of the automobile.

Further, as indicated by an arrow B in FIG. 22, in this detection, airmixed into the fluid to be detected can be reliably discharged from thefluid discharge port 11 in the liquid type detecting chamber 20 throughthe fluid outflow port 92 in the flow control plate 80. Therefore, airdoes not stay around the liquid type detecting sensor 24, and theinfluence on the detection can be prevented, contributing to accuratedetection.

Since the fluid introduction port 18 in the liquid type detectingchamber 20 and the fluid inflow port 90 in the flow control plate 80 arespaced from each other by a predetermined distance L1, as indicated byan arrow A in FIG. 22, air mixed into the fluid to be detected is movedthrough the space toward the outside of the flow control plate 80 and isdischarged to the outside of the liquid type detecting chamber 20through the fluid discharge port 11.

Therefore, the air does not enter the inside of the flow control plate80 and, thus, air does not stay around the liquid type detecting sensor24. This can realize the prevention of the influence of air on thedetection and thus can contribute to accurate detection.

Even though air enters the inside of the flow control plate 80, asindicated by an arrow C in FIG. 22, this air can be reliably dischargedfrom the fluid discharge port 11 in the liquid type detecting chamber 20through the fluid outflow port 92 in the flow control plate 80.Therefore, the air does not stay around the liquid type detecting sensor24. This can realize the prevention of the influence of air on thedetection and thus can contribute to accurate detection.

Further, as indicated by an arrow B in FIG. 22, the side wall in thevicinity of the fluid discharge port 11 in the liquid type detectingchamber 20 is provided in an approximately circular tube form, that is,in an approximately arc form. Therefore, air mixed into the fluid to bedetected is guided inward along the approximately arc-shaped side wall20 a in the liquid type detecting chamber 20 to the fluid discharge port11 in the liquid type detecting chamber 20 and is then discharged.

Therefore, the air does not stay around the fluid discharge port 11 inthe liquid type detecting chamber 20 and does not stay around the liquidtype detecting sensor 24. This can realize the prevention of theinfluence of air on the detection and thus can contribute to accuratedetection.

In order to realize the above function and effect, as shown in FIG. 22,the above predetermined distance L1, L2 is preferably 1.5 mm to 5 mm,more preferably 2 mm to 3.5 mm. Further, the distance L3 between thepair of side plate members 84, 86 in the flow control plate 80 and theliquid type detecting sensor 24 is preferably 5 mm to 10 mm, morepreferably 6 mm to 8 mm.

The size of the liquid type detecting chamber 20 is not particularlylimited.

Further, the material for constituting the liquid type detecting chamber20 is not particularly limited. For example, metals such as stainlesssteel including SUS 304, synthetic resins such as polyacetal (POM), andfiber reinforced resins such as FRPs are usable.

The material for constituting the flow control plate 80 is also notparticularly limited. For example, metals such as stainless steelincluding SUS 304, synthetic resins such as polyacetal (POM), fiberreinforced resins such as FRPs, and ceramics are usable.

In the flow rate/liquid type detectinq sensor device 10 according to thepresent invention, the circuit construction is as shown in FIG. 7.

In FIG. 7, a liquid type detecting liquid temperature sensor 26 in aliquid type detecting sensor heater 25 of a liquid type detecting sensor24 is connected to a liquid temperature sensor 28 through two resistors64, 66 to constitute a bridge circuit 68. The output of the bridgecircuit 68 is connected to the input of an amplifier 70. The output ofthis amplifier 70 is connected to the input of a computer 72constituting a detecting control unit.

A heater 74 in the liquid type detecting sensor heater 25 is constructedso that the applied voltage is controlled by the control of the computer72.

In the liquid type detecting sensor apparatus 10 having the aboveconstruction, for example, the liquid type of gasoline is detected asfollows.

First of all, control is carried out by a control unit (not shown) insuch a manner that the fluid to be detected is introduced into theliquid type detecting apparatus body 12, is passed through the firstpassage 14 and the fluid introduction port 18, and is allowed to flowinto the liquid type detecting chamber 20. Thereafter, the inflow of thefluid to be detected is stopped to allow the fluid to temporarily stayin the liquid type detecting chamber 20.

In this state, when the introduction of the fluid to be detected intothe liquid type detecting apparatus body 12 is stopped to allow thefluid to temporarily stay in the liquid type detecting chamber 20. Inaddition, the flow of the fluid to be detected within the liquid typedetecting chamber 20 is hindered by the flow control plate 1.Consequently, the flow of the fluid to be detected around the liquidtype detecting sensor 24, which is located within the flow control plate1 surrounded by the flow control plate 1, is instantaneously stopped.

In this state, as shown in FIGS. 7 and 8, a pulse voltage P is appliedto the heater 74 in the liquid type detecting sensor heater 25 for apredetermined period of time, for example, for 4 sec in the case of thisembodiment, by controlling the computer 72. Thereafter, a change intemperature of the analog output of a sensing part, that is, a sensorbridge circuit 68 is measured as shown in FIG. 7.

That is, as shown in FIG. 8, a voltage difference in a sensor bridgecircuit 68 before the application of a pulse voltage P to the heater 74in the liquid type detecting sensor heater 25 is sampled a predeterminednumber of times in one sec, for example, 256 times in the case of thisembodiment. As a result, and the average value thereof is determined asan average initial voltage V1. The value of the average initial voltageV1 corresponds to the initial temperature of the liquid type detectingliquid temperature sensor 26.

Thereafter, as shown in FIG. 8, a predetermined pulse voltage P (in thisembodiment, a voltage of 10 V for 4 sec) is applied to the heater 74 inthe liquid type detecting sensor heater 25. Next, after a predeterminedperiod of time (in this embodiment, after 3 sec), the peak voltage issampled a predetermined number of times (in this embodiment, 256 timesfor one sec), and the average of sampled data is determined as anaverage peak voltage V2. This average peak voltage V2 corresponds to apeak temperature of the liquid type detecting liquid temperature sensor26.

An voltage output difference V0 is obtained from the voltage differencebetween an average initial voltage V1 and an average peak voltage V2,that is,V0=V2−V1.

Specifically, in this way, as shown in FIG. 9, for predeterminedreference fluids, for example, for the heaviest (difficult to evaporate)gasoline A2 and the lightest (easy to evaporate) gasoline No. 7 in thisembodiment, calibration curve data for a temperature vs. voltage outputdifference correlation are previously obtained and are stored in thecomputer 72 constituting the control unit.

Thereafter, a proportional calculation is carried out with the computer72 based on the calibration curve data, and the type of the gasoline isdetected based on the voltage output difference V0 obtained for thefluid to be detected.

Specifically, as shown in FIG. 10, the voltage output Vout for thevoltage output difference V0 at the measuring temperature T of the fluidto be detected is correlated with the output voltage for the voltageoutput difference at the measuring temperature for a predeterminedthreshold reference fluid (in this embodiment, gasoline A2 and gasolineNo. 7) for correction.

Specifically, as shown in FIG. 10 (A), based on the calibration curvedata, at a temperature T, the voltage output difference V0−A2 forgasoline A2, the voltage output difference V0−7 for gasoline No. 7, andthe voltage output difference V0−S for the fluid to be detected areobtained.

As shown in FIG. 10 (B), a correlation with the properties of gasolinecan be established by bringing the liquid type output of the thresholdreference fluid in this case to a predetermined voltage, that is, by, inthis embodiment, bringing the liquid type output of gasoline A2 to 3.5 Vand bringing the liquid type output of gasoline No. 7 to 0.5 V, andobtaining the voltage output Vout of the fluid to be detected.

The liquid type of gasoline can be detected in an accurate and rapid(instantaneous) manner by comparing the voltage output Vout of the fluidto be detected with the data previously stored in the computer 72 basedon the calibration curve data.

In the above case, regarding the pulse width (pulse application time),in case of the detection of liquid type and the detection ofconcentration, since the fluid to be detected stays, avoidingoverheating is preferred. For this reason, the pulse width is preferablyless than 5 sec. On the other hand, in the case of the detection of flowrate, the fluid to be detected does not stay. Therefore, the flow ratecan be detected when the pulse width (pulse application time) is notless than 1 sec.

The above liquid type detecting method for gasoline utilize naturalconvection and utilizes such a principle that the kinematic viscosity ofgasoline has a correlation with the sensor output.

Further, regarding the liquid type detecting method for gasoline, in thedistillation properties of gasoline shown in FIG. 18, distillationproperties T30 to T70 have been found to provide a better correlationand thus are preferred.

Further, when the concentration of the fluid to be detected is measured,for example, in the case of an identification urea solution, as with thedetection of the liquid type, the voltage output Vout can be obtainedand correlated with the properties of urea.

The content of urea in the urea solution can be identified in anaccurate and rapid (instantaneous) manner by comparing the voltageoutput Vout of the urea solution to be identified with data stored in acomputer 72 based on previously measured calibration curve data for aurea solution as shown in FIG. 13.

FIG. 23 is a perspective view of another embodiment of the liquid typedetecting apparatus according to the present invention.

The construction of the liquid type detecting sensor apparatus 10 inthis embodiment is basically the same as the construction of the liquidtype detecting sensor apparatus 10 in the embodiment shown in FIG. 20.Accordingly, in FIGS. 23 and 20, like parts are identified with the samereference numerals, and detailed explanation will be omitted.

In the liquid type detecting sensor apparatus 10 in this embodiment, aheat insulating member 8 is interposed between the liquid type detectingapparatus body 12 and the liquid type detecting sensor apparatus body 12and the liquid type detecting chamber 20.

Since a heat insulating member is interposed between the liquid typedetecting apparatus body 12 and the liquid type detecting chamber 20,external temperature, external vibration, and external noise such asexternal electromagnetic waves do not affect the fluid to be detectedwithin the liquid type detecting chamber 20 and the liquid typedetecting sensor 24. Therefore, the liquid type and concentration of thefluid can be always detected with good accuracy.

For example, when the present invention is applied to the detection ofautomotive gasoline and light oils, the influence, on the detectingsensor, of the difference in temperature between winter and summer, thedifference in temperature derived from direct sunlight, snow and thelike, external noise such as electromagnetic waves, and, further,vibration during driving and impact caused, for example, by jumping ofstone, can be prevented by this heat insulating member. Therefore, theliquid type and concentration of the fluid can be always detected withgood accuracy.

The heat insulating member 8 is not particularly limited. For example,foamed synthetic resins such as polyethylene, polypropylene, andurethane, and glass wool are usable.

FIG. 14 is the same schematic diagram as FIG. 17, illustrating anembodiment in which a flow rate/liquid type detecting apparatus 1 havingthe above construction is applied to an automotive system.

The same component as those in FIG. 17 have the same reference numerals,and the detailed description thereof will be omitted.

In this automotive system 100, a flow rate/liquid type detectingapparatus 1 as shown in FIGS. 1 and 2 is provided within a fuel tank 108or on the upstream side of a fuel pump 110.

In this automotive system 100, a liquid type detecting sensor apparatus10 as shown in FIGS. 20 and 21 is provided within a fuel tank 103 or onthe upstream side of a fuel pump 110.

This automotive system 100 is constructed so that the liquid type andflow rate of the gasoline within the fuel tank 108 or on the upstreamside or downstream side of the fuel pump 110 (in this embodiment, thecase of the upstream side is shown for convenience of explanation) isdetected by the flow rate/liquid type detecting apparatus 1. As aresult, and ignition timing is adjusted by an ignition timing controlunit 122 through the control of a control unit 120 depending upon thetype of the gasoline.

This automotive system 100 is constructed so that the liquid type of thegasoline within the fuel tank 108 or on the upstream side or downstreamside of the fuel pump 110 (in this embodiment, the case of the upstreamside is shown for convenience of explanation) is detected by the liquidtype detecting sensor apparatus 10. As a result, ignition timing isadjusted by an ignition timing control unit 122 through the control of acontrol unit 120 depending upon the type of the gasoline.

Specifically, for example, when light (easy to evaporate) gasoline No. 7has been detected, the ignition timing is controlled to earlier one,while, when heavy (difficult to evaporate) gasoline A2 has beendetected, the ignition timing is controlled to delayed one.

Accordingly, in particular, even when an engine is started, particularlywhen an engine in which a catalyst device is not in a warmed state isstarted, the content of HCs in the exhaust gas can be reduced, and, atthe same time, fuel consumption can be improved, without causing areduction in torque.

FIG. 15 is the same schematic diagram as FIG. 17, illustrating anembodiment in which a flow rate/liquid type detecting apparatus 1 havingthe above construction is applied to an automotive system.

The same component as those in FIG. 17 have the same reference numerals,and the detailed description thereof will be omitted.

In this automotive system 100, a flow rate/liquid type detectingapparatus 1 as shown in FIGS. 1 and 2 is provided within a fuel tank 108or on the upstream side of a fuel pump 110.

In this automotive system 100, a liquid type detecting sensor apparatus10 as shown in FIGS. 20 and 21 is provided within a fuel tank 108 or onthe upstream side of a fuel pump 110.

This automotive system 100 is constructed so that the liquid type andflow rate of the gasoline within the fuel tank 108 or on the upstreamside or downstream side of the fuel pump 110 (in this embodiment, thecase of the upstream side is shown for convenience of explanation) isdetected by the flow rate/liquid type detecting apparatus 1. As aresult, and the compression ratio of gasoline is regulated by a gasolinecompression control unit 124 through the control of a control unit 120depending upon the type of the gasoline.

This automotive system 100 is constructed so that the liquid type of thegasoline within the fuel tank 108 or on the upstream side or downstreamside of the fuel pump 110 (in this embodiment, the case of the upstreamside is shown for convenience of explanation) is detected by the liquidtype detecting sensor apparatus 10. As a result, the compression ratioof gasoline is regulated by a gasoline compression control unit 124through the control of a control unit 120 depending upon the type of thegasoline.

Specifically, for example, when light (easy to evaporate) gasoline No. 7has been detected, the compression ratio is controlled to be lowered,while, when heavy (difficult to evaporate) gasoline A2 has beendetected, the compression ratio is controlled to be enhanced.

Accordingly, in particular, even when an engine is started, particularlywhen an engine in which a catalyst device is not in a warmed state isstarted, the content of HCs in the exhaust gas can be reduced, and, atthe same time, fuel consumption can be improved, without causing areduction in torque.

FIG. 16 is the same schematic diagram as FIG. 19, illustrating anembodiment in which a flow rate/liquid type detecting apparatus 1 havingthe above construction is applied to an automotive system using a ureasolution.

The same component as those in FIG. 19 have the same reference numerals,and the detailed description thereof will be omitted.

In this automotive system 100, a flow rate/liquid type detectingapparatus 1 as shown in FIGS. 1 and 2 is provided within a urea solutiontank 132 or on the upstream side of a fuel pump 134.

The urea concentration of the urea solution within the urea solutiontank 132 or on the upstream side or downstream side of the urea pump 134(in this embodiment, the case of the upstream side is shown forconvenience of explanation) is identified by the flow rate/liquid typedetecting apparatus 1. As a result, the concentration of urea sprayedtoward the upstream side of the catalyst device 116 is regulated sothat, in order to efficiently cause a reduction reaction on the upstreamside of the catalyst device 116 without causing solidification of theurea solution, for example, constantly, the urea solution comprises32.5% of urea and 67.5% of H₂O.

Therefore, the urea concentration of the urea solution in the urea tankcan be kept at a predetermined concentration, and, thus, the NOx in theexhaust gas can be decreased to a very low level by reduction.

In this automotive system 100, within the urea solution tank 132 or onthe upstream side of the urea pump 134, a liquid type detecting sensordevice 10 as shown in FIGS. 20 and 21 may be provided instead of theflow rate/liquid type detecting apparatus 1 as shown in FIGS. 1 and 2.

Also in this case, the urea concentration of the urea solution withinthe urea solution tank 132 or on the upstream side or downstream side ofthe urea pump 134 (in this embodiment, the case of the upstream side isshown for convenience of explanation) is identified by the liquid typedetecting sensor apparatus 10. As a result, the concentration of ureasprayed toward the upstream side of the catalyst device 116 is regulatedso that, in order to efficiently cause a reduction reaction on theupstream side of the catalyst device 116 without causing solidificationof the urea solution, for example, constantly, the urea solutioncomprises 32.5% of urea and 67.5% of H₂O.

Therefore, the urea concentration of the urea solution in the urea tankcan be kept at a predetermined concentration, and, thus, the NOx in theexhaust gas can be decreased to a very low level by reduction.

Preferred embodiments of the present invention have been describedabove. However, it should be noted that the present invention is notlimited to these preferred embodiments, and, for example, pulse voltageP and number of times of sampling may be properly changed.

In the above embodiments, explanation has been made about gasoline andurea solutions in an automotive system. However, various variations andmodifications may be made without departing from the object of thepresent invention. For example, the present invention can be applied toautomotive system using light oils or kerosene, as well as to casesusing fluids other than these fluids, for example, the case where, forexample, in plants, the type, concentration, and flow rate of a fluidare detected in apparatuses where an organic solution of a substancedissolved in an organic solvent is allowed to flow.

According to the present invention, the type, concentration and flowrate of fluids, for example, gasoline or a light oil as a fuel inautomobiles, and organic solutions in plants or the like can bedetected.

1. A flow rate/liquid type detecting apparatus for detecting the flowrate of a fluid and, at the same time, detecting any one of or both thetype of the fluid and the concentration of the fluid, comprising: a mainpassage through which a fluid to be detected flows; an auxiliary passagebranched from said main passage; a flow rate/liquid type detectingsensor device provided in said auxiliary passage; an auxiliary passageopening/closing valve provided in said auxiliary passage, forcontrolling the flow of the fluid to be detected into said flowrate/liquid type detecting sensor device; and a control unit forcontrolling said flow rate/liquid type detecting sensor and saidauxiliary passage opening/closing valve, said control unit beingconstructed so as to conduct control in such a manner that, inconducting any one of or both the detection of the type of said fluid tobe detected and the detection of the concentration of said fluid to bedetected, said auxiliary passage opening/closing valve is closed, andsaid fluid to be detected is allowed to temporarily stay within saidflow rate/liquid type detecting sensor device to conduct any one of orboth the detection of the liquid type and the detection of theconcentration, and in detecting the flow rate of the fluid to bedetected, said auxiliary passage opening/closing valve is opened toallow the fluid to be detected to flow into said flow rate/liquid typedetecting sensor device to detect the flow rate.
 2. The flow rate/liquidtype detecting apparatus according to claim 1, characterized in that anon-return valve is provided on the downstream side of said flowrate/liquid type detecting sensor device in said auxiliary passage. 3.The flow rate/liquid type detecting apparatus according to claim 1,characterized in that a main passage opening/closing valve forcontrolling the flow of said fluid to be detected into said main passageis provided in said main passage.
 4. The flow rate/liquid type detectingapparatus according to claim 3, characterized in that said control unitis constructed so as to conduct control in such a manner that: when theflow rate of said fluid to be detected is small, said main passageopening/closing valve is closed, and when the flow rate of said fluid tobe detected is large, said main passage opening/closing valve is opened.5. The flow rate/liquid type detecting apparatus according to claim 1,characterized in that an orifice is provided in the main passage.
 6. Theflow rate/liquid type detecting apparatus according to claim 1,characterized in that: said flow rate/liquid type detecting sensordevice comprises: a flow rate/liquid type detecting chamber for allowingthe fluid to be detected which has been introduced into a flowrate/liquid type detecting sensor device body to temporarily staytherein, a flow rate/liquid type detecting sensor heater provided withinsaid flow rate/liquid type detecting chamber, and a liquid temperaturesensor spaced by a given distance from said flow rate/liquid typedetecting sensor heater and provided within said flow rate/liquid typedetecting chamber, said flow rate/liquid type detecting sensor heatercomprising a heater and a flow rate/liquid type detecting liquidtemperature sensor provided in the vicinity of said heater, and saidflow rate/liquid type detecting apparatus is constructed so that: inconducting any one of or both the detection of the type of said fluid tobe detected and the detection of the concentration of said fluid to bedetected, a pulse voltage is applied to said flow rate/liquid typedetecting sensor heater for a predetermined period of time, the fluid tobe detected which temporarily stays within said flow rate/liquid typedetecting chamber is heated with the heater, and any one of or both theliquid type of the fluid and the concentration of the fluid aredetected, by a voltage output difference V0, corresponding to adifference in temperature between the initial temperature and the peaktemperature of said flow rate/liquid type detecting liquid temperaturesensor, in detecting the flow rate of said fluid to be detected, a pulsevoltage is applied to said flow rate/liquid type detecting sensor heaterfor a predetermined period of time, the fluid to be detected which flowsthrough said flow rate/liquid type detecting chamber is heated with theheater, and the flow rate is detected, by a voltage output differenceV0, corresponding to a difference in temperature between the initialtemperature and the peak temperature of said flow rate/liquid typedetecting liquid temperature sensor.
 7. The flow rate/liquid typedetecting apparatus according to claim 6, characterized in that thevoltage output difference V0 is the difference in voltage between anaverage initial voltage V1, which is determined by sampling the initialvoltage before the application of said pulse voltage by a predeterminednumber of times, and an average peak voltage V2, which is determined bysampling the peak voltage after the application of said pulse voltage bya predetermined number of times, that is, V0=V2−V1.
 8. The flowrate/liquid type detecting apparatus according to claim 6, characterizedin that said control unit is constructed so that: based on calibrationcurve data as a correlation between temperature and voltage outputdifference, for predetermined reference fluids previously stored in saidcontrol unit, any one of or both the liquid type and concentration ofsaid fluid to be detected are detected using said voltage outputdifference V0 obtained for said fluid to be detected.
 9. The fluidrate/liquid type detecting apparatus according to claim 6, characterizedin that said control unit is constructed so that: a voltage output Voutfor the voltage output difference V0 at a measuring temperature for saidfluid to be detected is corrected in a correlation with the outputvoltage for the voltage output difference at the measuring temperaturefor a predetermined threshold reference fluid.
 10. The flow rate/liquidtype detecting apparatus according to claim 6, characterized in thatsaid control unit is constructed so that: based on calibration curvedata as a correlation between temperature and voltage output difference,for predetermined reference fluids previously stored in said controlunit, the flow rate of said fluid to be detected is detected using saidvoltage output difference V0 obtained for said fluid to be detected. 11.The flow rate/liquid type detecting apparatus according to claim 6,characterized in that said flow rate/liquid type detecting sensor heateris a laminated flow rate/liquid type detecting sensor heater in which aheater and a flow rate/liquid type detecting liquid temperature sensorare laminated through an insulating layer.
 12. The flow rate/liquid typedetecting apparatus according to claim 6, characterized in that theheater in said flow rate/liquid type detecting sensor heater and saidflow rate/liquid type detecting liquid temperature sensor each areconstructed to as to come into contact with the fluid to be detectedthrough a metallic fin.
 13. The flow rate/liquid type detectingapparatus according to claim 6, characterized in that said liquidtemperature sensor is constructed so as to come into contact with thefluid to be detected through said metallic fin.
 14. A flow rate/liquidtype detecting apparatus for an automobile, for detecting the flow rateand type of gasoline or a light oil, characterized in that: the flowrate/liquid type detecting apparatus of claim 1 is provided within afuel tank or on the upstream side or downstream side of a fuel pump. 15.An automotive exhaust gas reduction apparatus comprising: the flowrate/liquid type detecting apparatus according to claim 1, which isprovided within a fuel tank or on the upstream side or downstream sideof a fuel pump; and an ignition timing control unit for regulatingignition timing based on the flow rate and type of the gasoline or lightoil, which is detected by said flow rate/liquid type detectingapparatus.
 16. An automotive exhaust gas reduction apparatus,comprising: the flow rate/liquid type detecting apparatus according toclaim 1, which is provided within a fuel tank or on the upstream side ordownstream side of a fuel pump; and a gasoline or light oil compressioncontrol unit for regulating the compression ratio of the gasoline orlight oil based on the flow rate and type of the gasoline or light oil,which is detected by said flow rate/liquid type detecting apparatus. 17.An automotive exhaust gas reduction apparatus, comprising: a ureasolution feed mechanism for feeding a urea solution to the upstream sideof a catalyst device, said urea solution feed mechanism comprising aurea solution tank for storing a urea solution, a urea pump, a ureaspray device for spraying the urea solution, which is supplied from saidurea pump, toward the upstream side of said catalyst device, and theflow rate/liquid type detecting apparatus according to claim 1, which isprovided within said urea tank or on the upstream side or downstreamside of said urea pump.
 18. A flow rate/liquid type detecting method fordetecting the flow rate of a fluid and, at the same time, detecting anyone of or both the type of the fluid and the concentration of the fluid,comprising the steps of: a flow rate/liquid type detecting apparatuscomprising: a main passage through which a fluid to be detected flows,an auxiliary passage branched from said main passage, and a flowrate/liquid type detecting sensor device provided in said auxiliarypassage, an auxiliary passage opening/closing valve provided in saidauxiliary passage, for controlling the flow of the fluid to be detectedinto said flow rate/liquid type detecting sensor device; conducting oneof or both of the steps of detecting the type of said fluid to bedetected and detecting the concentration of said fluid to be detected byclosing the auxiliary passage opening/closing valve and said fluid to bedetected is allowed to temporarily stay within said flow rate/liquidtype detecting sensor device to conduct any one of or both the detectionof the liquid type and the detection of the concentration, and detectingthe flow rate of the fluid to be detected, by opening said auxiliarypassage opening/closing valve to allow the fluid to be detected to flowinto said flow rate/liquid type detecting sensor device to detect theflow rate.
 19. The flow rate/liquid type detecting method according toclaim 18, further providing a non-return valve on the downstream side ofsaid flow rate/liquid type detecting sensor device in said auxiliarypassage.
 20. The flow rate/liquid type detecting method according toclaim 18, further providing a main passage opening/closing valve forcontrolling the flow of said fluid to be detected into said mainpassage.
 21. The flow rate/liquid type detecting method according toclaim 20, characterized in that control is carried out so that: when theflow rate of said fluid to be detected is small, said main passageopening/closing valve is closed, and when the flow rate of said fluid tobe detected is large, said main passage opening/closing valve is opened.22. The flow rate/liquid type detecting method according to claim 18,characterized in that an orifice is provided in the main passage. 23.The flow rate/liquid type detecting method according to claim 18,characterized in that said flow rate/liquid type detecting sensor devicefurther comprises: a flow rate/liquid type detecting chamber forallowing the fluid to be detected which has been introduced into a flowrate/liquid type detecting sensor device body to temporarily staytherein, a flow rate/liquid type detecting sensor heater provided withinsaid flow rate/liquid type, detecting chamber, and a liquid temperaturesensor spaced by a given distance from said flow rate/liquid typedetecting sensor heater and provided within said flow rate/liquid typedetecting chamber, said flow rate/liquid type detecting sensor heatercomprising a heater and a flow rate/liquid type detecting liquidtemperature sensor provided in the vicinity of said heater, and saidflow rate/liquid type detecting method comprising the steps of:conducting any one of or both the detection of the type of said fluid tobe detected and the detection of the concentration of said fluid to bedetected, applying a pulse voltage to said flow rate/liquid typedetecting sensor heater for a predetermined period of time, heating withthe heater, the fluid to be detected which temporarily stays within saidflow rate/liquid type detecting chamber, detecting any one of or boththe liquid type of the fluid and the concentration of the fluid, by avoltage output difference V0, corresponding to a difference intemperature between the initial temperature and the peak temperature ofsaid flow rate/liquid type detecting liquid temperature sensor, indetecting the flow rate of said fluid to be detected, applying a pulsevoltage to said flow rate/liquid type detecting sensor heater for apredetermined period of time, heating, with the heater, the fluid to bedetected which flows through said flow rate/liquid type detectingchamber, and detecting the flow rate by a voltage output difference V0,corresponding to a difference in temperature between the initialtemperature and the peak temperature of said flow rate/liquid typedetecting liquid temperature sensor.
 24. The flow rate/liquid typedetecting method according to claim 23, characterized in that thevoltage output difference V0 is the difference in voltage between anaverage initial voltage V1, which is determined by sampling the initialvoltage before the application of said pulse voltage by a predeterminednumber of times, and an average peak voltage V2, which is determined bysampling the peak voltage after the application of said pulse voltage bya predetermined number of times, that is, V0=V2−V1.
 25. The flowrate/liquid type detecting method according to claim 23, characterizedin that: based on calibration curve data as a correlation betweentemperature and voltage output difference, for predetermined referencefluids previously stored in said control unit, any one of or both theliquid type and concentration of said fluid to be detected are detectedusing said voltage output difference V0 obtained for said fluid to bedetected.
 26. The flow rate/liquid type detecting method according toclaim 23, including: correcting a voltage output Vout for the voltageoutput difference V0 at a measuring temperature for said fluid to bedetected in a correlation with the output voltage for the voltage outputdifference at the measuring temperature for a predetermined thresholdreference fluid.
 27. The flow rate/liquid type detecting methodaccording to claim 23, characterized in that: based on previously storedcalibration curve data as a correlation between temperature and voltageoutput difference for predetermined reference fluids, the flow rate ofsaid fluid to be detected is detected using said voltage outputdifference V0 obtained for said fluid to be detected.
 28. The flowrate/liquid type detecting method according to claim 23, characterizedin that said flow rate/liquid type detecting sensor heater is alaminated flow rate/liquid type detecting sensor heater in which aheater and a flow rate/liquid type detecting liquid temperature sensorare laminated through an insulating layer.
 29. The flow rate/liquid typedetecting method according to claim 23, characterized in that the heaterin said flow rate/liquid type detecting sensor heater and said flowrate/liquid type detecting liquid temperature sensor each areconstructed so as to come into contact with the fluid to be detectedthrough a metallic fin.
 30. The flow rate/liquid type detecting methodaccording to claim 23, characterized in that said liquid temperaturesensor is constructed so as to come into contact with the fluid to bedetected through said metallic fin.
 31. A flow rate/liquid typedetecting method for an automobile, for detecting the flow rate and typeof gasoline or a light oil, comprising: detecting the flow rate and typeof said gasoline or light oil within a fuel tank or on the upstream sideor downstream side of a fuel pump, by using the flow rate/liquid typedetecting method according to claim
 18. 32. An automotive exhaust gasreduction method, comprising the steps of: detecting the flow rate andtype of the gasoline or light oil within a fuel tank or on the upstreamside or downstream side of a fuel pump, by using the flow rate/liquidtype detecting method according to claim 18, and regulating an ignitiontiming based on the flow rate and type of the gasoline or light oilwhich is detected by said flow rate/liquid type detecting apparatus. 33.An automotive exhaust gas reduction method, comprising the steps of:detecting the flow rate and type of the gasoline or light oil within afuel tank or on the upstream side or downstream side of a fuel pump, byusing the flow rate/liquid type detecting method according to claim 18,and regulating the compression ratio of the gasoline based on the flowrate and type of the gasoline or light oil which is detected by saidflow rate/liquid type detecting apparatus.
 34. An automotive exhaust gasreduction method comprising the steps of: supplying a urea solution tothe upstream side of the catalyst device, through a urea solution feedmechanism comprising a urea solution tank for storing a urea solution, aurea pump, and a urea spray device for spraying the urea solution, whichis supplied from said urea pump, toward the upstream side of saidcatalyst device, and detecting the flow rate and urea concentration ofthe urea solution within said urea tank or on the upstream side ordownstream side of said urea pump, by using the flow rate/liquid typedetecting method according to claim
 18. 35. A liquid type detectingapparatus for detecting any one of or both the liquid type andconcentration of a fluid, comprising: a liquid type detecting chamberfor allowing a fluid to be detected which has been introduced into aliquid type detecting apparatus body to temporarily stay therein, aliquid type detecting sensor disposed within said liquid type detectingchamber, and a flow control plate provided within said liquid typedetecting chamber so as to surround said liquid type detecting sensor.36. The liquid type detecting apparatus according to claim 35,characterized in that said flow control plate has a fluid inflow portconfronted with a fluid introduction port in said liquid type detectingchamber and a fluid outflow port confronted with a fluid discharge portin said liquid type detecting chamber.
 37. The liquid type detectingapparatus according to claim 35, characterized in that the fluidintroduction port in said liquid type detecting chamber and the fluidinflow port in said flow control plate are spaced from each other by apredetermined distance, and the fluid discharge port in said liquid typedetecting chamber and the fluid outflow port in said flow control plateare spaced from each other by a predetermined distance.
 38. The liquidtype detecting apparatus according to claim 35, characterized in thatthe side wall in the vicinity of the fluid discharge port in said liquidtype detecting chamber is provided in an approximately arc form.
 39. Theliquid type detecting apparatus according to claim 35, characterized inthat said liquid type detecting chamber is provided with anapproximately circulate tube side wall, and the fluid introduction portand the fluid discharge port in said liquid type detecting chamber areprovided so as to confront said side wall.
 40. The liquid type detectingapparatus according to claim 35, characterized in that a heat insulatingmember is interposed between said liquid type detecting apparatus bodyand said liquid type detecting chamber.
 41. The liquid type detectingapparatus according to claim 35, characterized in that: said liquid typedetecting sensor comprises: a liquid type detecting sensor heaterprovided within said liquid type detecting chamber, and a liquidtemperature sensor spaced by a given distance from said liquid typedetecting sensor heater and provided within said liquid type detectingchamber, said liquid type detecting sensor heater comprising a heaterand a liquid type detecting liquid temperature sensor provided in thevicinity of said heater, and in conducting any one of or both thedetection of the type of said fluid to be detected and the detection ofthe concentration of said fluid to be detected, a pulse voltage isapplied to said liquid type detecting sensor heater for a predeterminedperiod of time to heat, the fluid to be detected which temporarily stayswithin said liquid type detecting chamber is heated with the heater, andany one of or both the liquid type of the fluid and the concentration ofthe fluid are detected, by a voltage output difference V0, correspondingto a difference in temperature between the initial temperature and thepeak temperature of said liquid type detecting liquid temperaturesensor.
 42. The liquid type detecting apparatus according to claim 41,characterized in that the voltage output difference V0 is the differencein voltage between an average initial voltage V1 determined by samplingthe initial voltage before the application of said pulse voltage by apredetermined number of times and an average peak voltage V2 determinedby sampling the peak voltage after the application of said pulse voltageby a predetermined number of times, that is, V0=V2−V1.
 43. The liquidtype detecting apparatus according to claim 41, characterized in thatany one of or both the liquid type and concentration of said fluid to bedetected are detected using said voltage output difference V0 obtainedfor said fluid to be detected, based on previously stored calibrationcurve data as a correlation between temperature and voltage outputdifference for predetermined reference fluids.
 44. The liquid typedetecting apparatus according to claim 41, characterized in that: avoltage output Vout for the voltage output difference V0 at a measuringtemperature for said fluid to be detected is corrected in a correlationwith the output voltage for the voltage output difference at themeasuring temperature for a predetermined threshold reference fluid. 45.The liquid type detecting apparatus according to claim 41, characterizedin that said liquid type detecting sensor heater is a laminated liquidtype detecting sensor heater in which a heater and a liquid typedetecting liquid temperature sensor are laminated through an insulatinglayer.
 46. The liquid type detecting apparatus according to claim 41,characterized in that the heater in said liquid type detecting sensorheater and said liquid type detecting liquid temperature sensor each areconstructed so as to come into contact with the fluid to be detectedthrough a metallic fin.
 47. The liquid type detecting apparatusaccording to claim 41, characterized in that said liquid temperaturesensor is constructed so as to come into contact with the fluid to bedetected through said metallic fin.
 48. A liquid type detectingapparatus for an automobile, for detecting the type of gasoline or alight oil, comprising: the liquid type detecting apparatus according toclaim 35, which is provided within a fuel tank or on the upstream sideor downstream side of a fuel pump.
 49. An automotive exhaust gasreduction apparatus, comprising: the liquid type detecting apparatusaccording to claim 35, which is provided within a fuel tank or on theupstream side or downstream side of a fuel pump; and an ignition timingcontrol unit for regulating ignition timing based on the type of thegasoline or light oil, which is detected by said liquid type detectingapparatus.
 50. An automotive exhaust gas reduction apparatus,comprising: the liquid type detecting apparatus according to claim 35,which is provided within a fuel tank or on the upstream side ordownstream side of a fuel pump; and a gasoline or light oil compressioncontrol unit for regulating the compression ratio of the gasoline orlight oil based on the type of the gasoline or light oil which isdetected by said liquid type detecting apparatus.
 51. An automotiveexhaust gas reduction apparatus comprising: a urea solution feedmechanism for feeding a urea solution to the upstream side of a catalystdevice, said urea solution feed mechanism comprising a urea solutiontank for storing a urea solution, a urea pump, a urea spray device forspraying the urea solution, which is supplied from said urea pump,toward the upstream side of said catalyst device, and the liquid typedetecting apparatus according to claim 35, which is provided within saidurea tank or on the upstream side or downstream side of said urea pump.52. A liquid type detecting method for detecting any one of or both theliquid type and concentration of a fluid, comprising the steps of:providing a liquid type detecting apparatus comprising: a liquid typedetecting chamber for allowing a fluid to be detected which has beenintroduced into a liquid type detecting apparatus body to temporarilystay therein, a liquid type detecting sensor disposed within said liquidtype detecting chamber, and a flow control plate provided within saidliquid type detecting chamber so as to surround said liquid typedetecting sensor, the method further comprising the steps of: stoppingthe introduction of the fluid to be detected into said liquid typedetecting apparatus body, allowing the fluid to be detected totemporarily stay within said liquid type detecting chamber, andconducting the detection of ay one of or both the liquid type andconcentration of the fluid to be detected.
 53. The liquid type detectingmethod according to claim 52, characterized in that said flow controlplate has a fluid inflow port confronted with a fluid introduction portin said liquid type detecting chamber and a fluid outflow portconfronted with a fluid discharge port in said liquid type detectingchamber.
 54. The liquid type detecting method according to claim 52,characterized in that the fluid introduction port in said liquid typedetecting chamber and the fluid inflow port in said flow control plateare spaced from each other by a predetermined distance, and the fluiddischarge port in said liquid type detecting chamber and the fluidoutflow port in said flow control plate are spaced from each other by apredetermined distance.
 55. The liquid type detecting method accordingto claim 52, characterized in that the side wall in the vicinity of thefluid discharge port in said liquid type detecting chamber is providedin an approximately arc form.
 56. The liquid type detecting apparatusaccording to claim 52, characterized in that said liquid type detectingchamber is provided with an approximately circular tube side wall, andthe fluid introduction port and the fluid discharge port in said liquidtype detecting chamber are provided so as to confront said side wall.57. The liquid type detecting method according to claim 52,characterized in that a heat insulating member is interposed betweensaid liquid type detecting apparatus body and said liquid type detectingchamber.
 58. The liquid type detecting method according to claim 52,characterized in that: said liquid type detecting sensor comprises: aliquid type detecting sensor heater provided within said liquid typedetecting chamber, and a liquid temperature sensor spaced by a givendistance from said liquid type detecting sensor heater and providedwithin said liquid type detecting chamber, said liquid type detectingsensor heater comprising a heater and a liquid type detecting liquidtemperature sensor provided in the vicinity of said heater, and inconducting any one of or both the detection of the type of said fluid tobe detected and the detection of the concentration of said fluid to bedetected, applying a pulse voltage to said liquid type detecting sensorheater for a predetermined period of time to heat the fluid to bedetected which temporarily stays within said liquid type detectingchamber is heated with the heater, and detecting any one of or both theliquid type of the fluid and the concentration of the fluid, by avoltage output difference V0, corresponding to a difference intemperature between the initial temperature and the peak temperature ofsaid liquid type detecting liquid temperature sensor.
 59. The liquidtype detecting method according to claim 58, characterized in that thevoltage output difference V0 is the difference in voltage between anaverage initial voltage V1 determined by sampling the initial voltagebefore the application of said pulse voltage by a predetermined numberof times and an average peak voltage V2 determined by sampling the peakvoltage after the application of said pulse voltage by a predeterminednumber of times, that is, V0=V2−V1.
 60. The liquid type detecting methodaccording to claim 58, characterized in that any one of or both theliquid type and concentration of said fluid to be detected are detectedusing said voltage output difference V0 obtained for said fluid to bedetected, based on previously stored calibration curve data as acorrelation between temperature and voltage output difference forpredetermined reference fluids.
 61. The liquid type detecting methodaccording to claim 58, including: correcting a voltage output Vout forthe voltage output difference V0 at a measuring temperature for saidfluid to be detected in a correlation with the output voltage for thevoltage output difference at the measuring temperature for apredetermined threshold reference fluid.
 62. The liquid type detectingmethod according to claim 58, characterized in that said liquid typedetecting sensor heater is a laminated liquid type detecting sensorheater in which a heater and a liquid type detecting liquid temperaturesensor are laminated through an insulating layer.
 63. The liquid typedetecting method according to claim 58, characterized in that the heaterin said liquid type detecting sensor heater and said liquid typedetecting liquid temperature sensor each are constructed so as to comeinto contact with the fluid to be detected through a metallic fin. 64.The liquid type detecting method according to claim 58, characterized inthat said liquid temperature sensor is constructed so as to come intocontact with the fluid to be detected through said metallic fin.
 65. Aliquid type detecting method for an automobile, for detecting the typeof gasoline or a light oil, comprising: detecting the type of saidgasoline or light oil within a fuel tank or on the upstream side ordownstream side of a fuel pump, by using the liquid type detectingmethod according to claim
 52. 66. An automotive exhaust gas reductionmethod, comprising the steps of: detecting the type of the gasoline orlight oil within a fuel tank or on the upstream side or downstream sideof a fuel pump, by using the liquid type detecting method according toclaim 52, and regulating an ignition timing based on the type of thegasoline or light oil which is detected by said liquid type detectingapparatus.
 67. An automotive exhaust gas reduction method, comprisingthe steps of: detecting the type of the gasoline or light oil within afuel tank or on the upstream side or downstream side of a fuel pump, byusing the liquid type detecting method according to claim 52, andregulating the compression ratio of the gasoline based on the type ofthe gasoline or light oil which is detected by said liquid typedetecting apparatus.
 68. An automotive exhaust gas reduction methodcomprising the steps of: supplying a urea solution to the upstream sideof the catalyst device, through a urea solution feed mechanismcomprising a urea solution tank for storing a urea solution, a ureapump, and a urea spray device for spraying the urea solution, which issupplied from said urea pump, toward the upstream side of said catalystdevice, and detecting the urea concentration of the urea solution withinsaid urea tank or on the upstream side or downstream side of said ureapump, by using the liquid type detecting method according to claim 52.